178 Review Department.-Observations at the Magnetical and Meteorological Observatory, Toronto. a more permanent and comparative character are neces-of Ordnance, and its military corps. This recommendasary, before a system founded on general laws can be tion, having been strengthened by the support of the framed. For the purpose of obtaining the absolute value Royal Society, was acceded to by the Government; and of the magnetic elements, fixed magnetic Observatories, under the direction of a Committee of the Royal Society, under the control of attentive observers, become indis- the necessary instruments were prepared, and a code of pensable, and through them the nature of all magnetic instructions relating to their use and objects drawn up, disturbances, and the causes of those perturbations of the published, and subsequently modified. The Antarctic magnetic elements which occasionally occur, may, by expedition was entrusted with the charge of the Obsermeans of simultaneous and systematic observations, both vatory at Van Dieman's Land during its first two years' as to time and as to instruments, be possibly discovered. operations, and the other three were each placed under On the continent of Europe, establishments for the accom- the management of a lieutenant of artillery, with whom plishment of these objects have been formed; but in was united three (afterwards four) non-commissioned Britain individual zeal alone was engaged in the inquiry, officers, and two gunners, to all of whom increased allowuntil 1836, when the attention of her philosophers was ances were made. The sum of £100 for each Obsermore specifically drawn to the subject, by a letter from vatory was allotted for incidental expenses, making the Baron Humboldt to the late Duke of Sussex-an appeal total charge for each about £392 per annum. which was met with every respect and consideration. The officers appointed to the charge of the ObservaIn 1837, the University of Dublin, at the instance of tories were ordered to Dublin, to receive instructions in Dr. Lloyd, established an Observatory for all researches the manipulation of the instruments in the Observatory connected with terrestrial magnetism and meteorology; there, which were similar to those ordered for the Cothe same year the Government allotted a site for a simi-lonies; and in autumn, 1839, they quitted England for lar establishment at Greenwich, to be placed under the control of the Astronomer Royal, and shortly afterwards a third was established at Kelso, in Scotland, at the private expense of Sir Thomas M. Brisbane, Bart. de novo, by Lieutenant Younghusband, who continued their respective destinations. The officer appointed to Canada was Lieutenant C. J. B. Riddell, who, being obliged to return to England in February, 1841, in consequence of ill-health, was temporarily succeeded by The British Association for the Advancement of SciLieutenant Younghusband, who acted until the arrival of ence commenced in 1834 a magnetic survey of the BriLieutenant Lefroy in September, 1842. The latter offitish Islands, which was completed on its own responsi-cer proceeded in April, 1843, on a magnetic survey bility in the two following years. The result was pub-within the Hudson's Bay territories, and was succeeded, lished in its annual report of 1838, and the work was followed up in other countries at the expense of their in charge to nearly the end of 1844. respective governinents. In 1838, on consideration of The observations made at the Colonial Observatories a report made of the progress of the researches regarding having, according to instructions, been forwarded in the geographical distribution of the magnetic forces on monthly reports to the Ordnance, were, at the request of the surface of the globe, the British Association called the Royal Society, ordered by the Treasury to be reupon the Government to aid the prosecution of the in- duced and published, under the superintendence of Lieut.quiry in more remote parts of the earth, and, in conse-Colonel Sabine, assisted by Lieutenant Riddell, and four quence, a naval expedition was equipped in 1839, for a military clerks, who were non-commissioned officers of magnetic survey of the higher latitudes of the southern the Royal Artillery. hemisphere. The Association, at the same time, recom- The results which have already been laid before the mended that similar magnetic, and also meteorological public, consequent on these arrangements, have been the researches, should be accomplished by fixed Observa-publication-Firstly, of the magnetic observations made tories at certain stations of prominent magnetic interest by the Antarctic expedition on its passage to Kerguelen within the limits of the Colonies,-Canada and Van Dieman's Land, as approximate to the points of the greatest intensity of the magnetic forces in their respective hemispheres-St. Helena, as approximate to the point of least intensity on the globe, and the Cape of Good Hope, as a station where the secular changes of tories, and by the expedition, on days of unusual magthe magnetic elements were peculiarly interesting, were named; and it was suggested that the Observatories should be placed under the superintendence of the Board Island, and during the first and second years of its operations at sea, within the Antarctic circle, and printed at the expense of the Royal Society, in the Philosophical Transactions respectively for 1842, 43, and '44; 2dly, Of observations made in 1840 and '41, at the Observa netic disturbance, for comparison with each other, and with similar observations made simultaneously in different parts of the globe, printed by the Government in 1843'; Review Department.—Observations at the Magnetical and Meteorological Observatory, Toronto. 179 and 3dly, A very useful work by Lieutenant Riddell, The instruments are supported by massive stone pillars, containing magnetic instructions for the use of portable each formed of a single stone, about six or seven feet magnetic instruments, and for fixed magnetic Observa- long, imbedded in masonry to the depth of three feet. tories, printed by the Government in 1844. the good conduct, intelligence, and zeal of the men, and the thoroughly efficient and trustworthy manner in which they performed their duties, are spoken of in terms honorable to the distinguished corps to which they belong. Lieut.-Colonel Sabine has contributed (with the assistance of Lieutenant Riddell), about 100 pages of preliminary observations, under the head of "Adjustments, Abstracts, and Comments." To give even an outline of the immense mass of tabular information here submitted to the scientific reader, is far beyond our limited space, without serious encroachment upon the other departments of our Journal We would, if it were within our power, submit a few extracts, or the substance of such comments, where they immediately seem to call for particular attention, but we must keep within the bounds we have prescribed for ourselves. The foregoing details we have condensed from Lieut.Lieutenant Riddell, on his arrival in Canada, exa- Colonel Sabine's introduction to the work, which commined different localities which were suggested to him as prises the observations made in 1840, 41, and '42, by convenient sites for his Observatory. The preference the Lieutenants in charge, whose assiduity, efficiency, was finally given to Toronto, where he was offered two- and talents, are highly commended by the gallant and sciand-a-half acres of ground belonging to King's College, entific editor. Nor is it the less gratifying to find that on the sole condition that the buildings erected should be appropriated only for an Observatory, and revert to the College when discontinued. This offer was accepted, and the new buildings occupied in September, 1840. In the mean time a temporary Observatory was formed in a small unoccupied barrack in the city. The new Observatory is situated in lat. 43°, 49" 35", and long. 79°, 21" 30", on a rising ground, about half a mile north of the city, 300 yards west of the University, and 1073 feet above the surface of Lake Ontario, or 3413 feet above the sea. The buildings consist-1st, Of an Observatory, having two apartments, one for the instruments, 50 feet by 20,―the other, an office or computing room, 18 feet by 12, with a vestibule or hall, 12 by 6-the transit theodolite occupying a small circular room, connected by a covered passage with the instrument room, and placed at We notice from the observations made on the subject a sufficient distance from it to obtain a view of the lower of magnetic declination, that the following practical inferculmination of some of the circumpolar stars; 2d, A ences are derived for the instruction of persons who may detached building, with a room 18 feet by 12, partly sunk have occasion to employ the compass in surveying, and under ground, with a view to uniform temperature, for other similar purposes in Canada:-1st. That large deviaexperimental determinations and observations of absolute tions from the mean monthly direction of the needle, at the intensity. It is situated about 80 feet from the Observa-same hours, are least likely to occur from noon to 4 P.M. tory, so that the instruments placed in it, may neither 2d. That at all other hours of the day, the liability to the affect, nor be affected, by the magnets in the Observatory; occurrence of deflections exceeding five to six minutes 3d, An anemometer house, constructed so as to support from the mean direction at the same hours, is about three the vane and pressure plate of Oster's anemometer, at a times as great as at the hours of two and four P.M.; at height exceeding 30 feet above the roof of the Observa-six P.M., the liability, as it may be estimated from the tory, and above the neighbouring trees; 4th, A small two hourly observations, is about one observation in shed for the inclination circle-and 5th, Barracks for the twenty-eight, and at eight and ten P.M., rather greater. officers and detachment. The whole of the ground 3d. That the disturbances are usually deflections of the granted by the College is enclosed by a picketing. The north ends of the needle to the west in the forenoon, and buildings 1 to 4 are at the eastern end, within an inner to the east from six P.M., to midnight, inclusive. inclosure; the barracks for the officer and party are at One of the principal objects to be attained from the the western end. The Observatory is built of 12-inch establishment of the fixed Observatories, was the elucilogs, rough cast on the outside, and plastered on the in-dation of the laws of the irregular fluctuations of the side, the laths being attached to battens projecting two magnetic elements, and the determination of their local inches from the logs, so as to leave a stratum of air be- or universal character. To effect this, all the magnettween the logs and plaster. The doors and windows are ometers were to be observed on certain days simultanedouble, and the outer door has the further protection of a ously at certain short intervals, and for twenty-four hours closed porch. The small room, or office, is provided together. Twelve days, entitled Term days, were named with an open fire-place, adapted for a wood fire; the in each year, one in each month, for this kind of obserinstrument room has neither stove nor fire-place. No vation; the intervals between the observations being iron whatever was used in the structure, the nails being five minutes for the declinometer, and ten for the magof copper, and the locks and other fastenings of brass. netometers. Other national magnetic Observatories were 180 Periscope. On the Diagnosis of Aneurisms of the Aorta. Aus If the aneurism be so small as not to have arrived at the invited to co-operate in these simultaneous observations; walls of the chest, it may be recognized still by its impulse and this invitation was, among others, quickly responded and by a dull sound on percussion, which indicates that the to by the directors of the Observatories at Boston and corresponding portion of lung is pushed on one side. Philadelphia. The observations of these latter bodies, cultation also reveals a double "bruit de choc," and a dry as far as they have been made, have been communicated friction sound; a to-and-fro sound, in fact, is sometimes interposed between the systolic and diastolic braits. If the to Lieut.-Colonel Sabine, and the whole have been pro-site of the aneurism, and the heart be simultaneously exjected upon a similar scale for comparative reference amined, it is easily perceived that the sound given out by the aneurism is different both in seat and quality from that with those made at Toronto. The remarkable harmony of the heart. The diastolic sound of the aneurism does not in the curves of the three American Observatories on coincide with the second sound of the heart, but precedes it. When the aneurism of the origin and ascending portion every one of the Term days, attests the reality of the pheof the artery consists in simple dilatation of the arterial tunomena, of which each affords an independent represen-nics, it gives rise to certain peculiar signs. Auscultation tation. The perturbations which took place in Toronto at the right border of the sternum, and over the cartilages in the magnetic direction, and in the intensity of the mag-of the second and third ribs on the right side, reveals the netic force, are obviously common to a large portion of existence of only one bruit, combined with an impulse, which is synchronous with, and in some cases difficult the North American continent. To effect a comparison to distinguish from the systole of the ventricles. of similar simultaneous observations made in Europe, the The aneurismal bruit, however, is heard almost as displates containing the American curves, embody also the tinctly behind as before-while the heart's action is nearly results obtained from the observations made on the Terminaudible in the back; moreover, the bruit depending on the heart is heard on the left side, between the scapula and days, at Prague or Breslau, and which embody the mag-spine-the aneurismal bruit on the right. This difference netic perturbations common throughout the largest portion in the sounds in the posterior aspect of the thorax is sufficiof the European continent. The correspondence so strik-ently diagnostic. There is in some cases but little pain in simple dilatation ingly manifested in the fluctuations of the declination and of the ascending aorta; and in general it gives rise to no horizontal force in America, and which has its counter-more than a sensation of uneasiness and fulness under the In this respect it differs widely from aneurism part in Europe, is not found to prevail in the same de- sternum. gree between the curves of the two Continents, when depending upon erosion of the arterial tunics. exhibited in comparison. Nevertheless, instances are not unfrequent of individual perturbations common to both Continents, having their culminating points at the same observation instant. There are sometimes disturbances in the same direction in both Continents, and sometimes in opposite directions. On the other hand, there are perturbations, and occasionally of considerable magnitude, on the one Continent, of which no trace is visible in the observations of the other. If the ascending aorta becomes the seat of considerable dilatation, or be enlarged by aneurism from rupture of its coats, the trachea is usually pushed slightly to the left side. A difference in the pulse in the two wrists is generally considered to be a diagnostic sign of aneurism of the aorta; this sign, however, is equally perceptible in simple arteries, and therefore has no value as a diagnostic. Dyspnea is one of the signs of aneurism; but when the tumour is situated in the ascending portion, it is not constant, but occurs only upon exertion or mental disturbance. If, however, the aneurism be sufficiently large to compress the principal divisions of the bronchi, the difficulty of breathing is continuHaving thus premised these general observations on ous, and becomes suffocative when muscular exertion is made; and in such cases the compression is indicated by the the work before us, we purpose, in our next, to present existence of a sibilous rale. When the walls of the bronto our readers some of the tabular results, which have chi become inflamed in consequence of the pressure, expecbeen deduced from the extended observations made and toration of tenacious mucus is superadded, and should warn us of the near approach of one of the terminations of the conducted in so creditable a manner to the parties in-disease, by rupture into the respiratory passages. vested with the charge. PRACTICE OF MEDICINE AND PATHOLOGY. ON THE DIAGNOSIS OF ANEURISMS OF THE In some cases the compression is not limited to the bronchi, but is exercised also upon the origin of the pulmonary arteries, particularly those on the right side; the dyspnea is then greatly aggravated, and the patient usually is attacked with hemoptysis. Lividity of the countenance is likewise present in these cases, on account of the deficient arterialization of the blood. The dyspnea in cases of aneurism of the origin of the By M. GENDRIN, Physician to La Pitié, Paris. aorta, is often the result of a coincident affection of the heart The present memoir comprises the diagnosis of aneurism or pericardium. Valvular disease and endocarditis form a of each of the three anatomical divisions of the aorta.- serious complication, as they induce in general a greater or Aneurism of the ascending portion, when it becomes evident less amount of a ventricular hypertrophy. The proficient externally, appears in the form of an hemispherical circum-in auscultation will not confound the symptoms of these scribed swelling, which pulsates isochronously with the complications with those of the original lesion; but still the heart. The skin is not altered in colour till the latter pe-diagnosis often becomes sufficiently difficult to require atriods of the disease. The patient generally complains of tentive investigation. pain in the tumour, which is increased during the systole of the heart, and which becomes oftentimes much increased by motion, and during the digestive process. The tumour is more or less painful to the touch, and pulsates strongly, It is a common opinion that the asthmatic paroxysm frequently depends upon disease of the heart and large vessels; it is not difficult, however, to distinguish real asthma from the dyspnoea of cardiac disease. The former Periscope. On the changes in Urine effected by Disease. 181 is truly paroxysmal, and oftentimes periodic, the intervals Tho signs of aneurism of the descending aorta are perceivbeing in some cases of great duration. There is, moreover, ed more plainly in the back than in the front of the chest. constantly present a cough, with expectoration and sibilant They are, as perceived in this situation, the double "bruit rales. In general, emphysema may be recognised by the de choc," together with a rough or sibilant friction sound. physical signs proper to that lesion. The diagnosis is fur- If these signs are very evident, no doubt need be entertainther elucidated by the absence of the special signs of aneu-ed of the existence of aneurism, especially if they are conrism or morbus cordis. joined to a tearing, gnawing pain along the spinal column, which is aggravated by motion of the upper extremities.Ranking's Abstract of the Medical Sciences. Again, angina pectoris is frequently referred to simple or aneurismal inflammation of the origin of the aorta. This also is an error. The symptoms of the two affections are distinct; for instance, the substernal constriction, and the neuralgic pain extending down the left arm, which are the essential symptoms of angina, are not necessarily present in an urism. Sudden death also is common in the former but not in the latter. [This will doubtless appear a bold asser- By E. J. SHEARMAN, M.D., Member of the Royal College of Phy. tion, but it is nevertheless the author's exact expression.] sicians of London, &c. ON THE CHANGES IN THE URINE EFFECTED BY (Read at the Sheffield Medical Society, March 20, 1845.) (Continued from page 138.) 3. We will now endeavour to point out the easiest modes of detecting the contents of diseased urine, under the following divisions-viz., 1. Crystalline contents; 2. Colouring urinometer, test tubes, watch glasses, spirit lamp, and a good The only necessary apparatus for these experiments are, a achromatic microscope. The re-agents are well known to the profession. CRYSTALLINE CONTENTS. Aneurism of the arch of the aorta is generally situated in the interval comprised between the origin of the arteria innominata and the left carotid and subclavian. The projection of the tumour shows itself in the space included between the internal third of the second right rib, and the corresponding portion on the left side. It is also sometimes perceived in the hollow between the insertion of the sterno-matters; 3. Organic deposits. mastoid muscles. When the aneurismal tumour of this part of the artery becomes apparent to the eye, it gives rise to symptoms identical with those lately mentioned. The aspect of the tumour is the same, and the pain has the same character, with the exception that it is perceived, at the summit of the sternum, and between the shoulders. If the Urea. When this is in excess, the urine is of a high spetumour does not project externally, its diagnosis is a matter cific gravity, and generally of a reddish colour. By adding of considerable difficulty, especially when the posterior an equal quantity of nitric acid in a watch glass, it crystalportion of the arch is the part affected. The dulness on lizes at the bottom very soon as nitrate of urea; when the percussion in deep-seated aneurisms of the arch is some-urea is in excess, it soon becomes solid. By combining with what obscure, and is therefore of little service as a diag-two atoms of water, urea is converted into carbonate of amnostic sign. The auscultatory phenomena are similar to monia; and this accounts for urine becoming alkaline and those exhibited in aneurism of the ascending aorta, but are pungent soon after it has cooled. A little excess of mucus perceived in a different situation. In front they are heard aids this process. at the summit of the sternum, and under the junction of the clavicle and first rib with that bone; behind, they are most evident on a level with the second rib, and close to the spinal column. Uric acid or Lithic acid is the substance of which the greatest number of urinary calculi is composed. The urine is high-coloured; specific gravity generally above 1.020, and contains an excess of urea. Uric acid, acting on the phosThe deviation of the trachea is more decisive in aneu-phate of soda and ammonia, (or microcosmic salt,) existing risms of the arch than in those of the ascending portion, in urine, is decomposed; urate of ammonia is formed, and but the apex of the heat is not displaced, as is occasionally phosphoric acid set free, which is the cause of the acid re-acthe case in the latter. The pulse is deceptive as a diag-tion of urine. So that uric acid is usually found in the form nostic symptom taken per se, but is a valuable accessory of urate of ammonia. To detect it-warm the urine containsign, and is one by which we may judge of the exact site of the disease. If, as is commonly the case, the innominata is implicated in the aneurismal tumour, the pulse is feeble in the right wrist. When on the other hand, the left pulse is the feebler of the two, we may conceive that the disease is located at the left extreme of the arch. The dyspnea in aneurism of the arch, is subject to the same conditions as when the ascending aorta is the seat of the disease. It does not differ from the dyspnea, which occurs in the latter case, unless the trachea be compressed. In that case, inspiration is remarkably difficult, and is accompanied by a whistling sound. In some cases the voice is enfeebled, or even entirely extinguished. ing urate of ammonia in a watch glass, and the uric acid becomes deposited at the bottom of the glass, and, when viewed by the microscope, is seen crystallized in red rhombic prisms. It is familiarly known by the names of yellow and red sand. Heat does not dissolve it. Pure uric acid is only soluble in 10,000 parts of water at 60 deg., and is insoluble in alcohol. Liquor potassæ dissolves it, forming urate of potass. Hydrochloric and acetic acids have no action. It is dissolved by nitric acid; and by evaporation, a pink colour (becoming a rich purple on being held over the vapour of ammonia) is produced. This is purpurate of ammonia. Exposed to heat in a platinum spoon, it burns, evolving an odour of bitter almonds, and leaving phosphate of soda and lime behind. Hippuric acid.-This is rich in carbon, and found plentiadd excess of hydrochloric acid; uric acid and hippuric acid will then be separated, and fall to the bottom; pour off the supernatant fluid, and wash in cold water; boil the residue in alcohol, in which hippuric acid is soluble, and uric acid is not, from which it gradually crystallizes in delicate coloured needles, very visible under the microscope. It is soluble in four hundred parts of water at 60 deg. Of all forms of aortic aneurism, those affecting the descending part of the vessel are the most difficult to recog-fully in the horse and cow. Evaporate the urine to a syrup, nize. It is difficult to distinguish the impulse and the bruit, when perceived in front from those of the heart itself, but we may sometimes arrive at a diagnosis by compressing the abdominal aorta. This causes the second sound to cease, if it originates in the artery, but has no influence upon the cardiac bruits. If, however, to the double "bruit de choc," perceived in the front of the chest, is added a sibilant râle, and if the second sound slightly precedes the diastole of the heart, the existence of an aneurism may be considered certain Urate of ammonia.-This is the lateritious sediment, soluble in 480 parts of water at 60 deg. The colour of this urine is from pale to crimson; specific gravity from 1.012 to 1.025; 182 Periscope. On the changes effected in the Urine by disease. it often contains floating masses. The deposits are from fawn| Ammonia, or phosphate of soda, or microscomic salt.— colour up to purple; they never appear until the urine has This is usually decomposed by uric acid in the bladder : urate cooled, and disappear by heat. Liquor ammonia and liquor of ammonia is formed, the phosphoric acid being set at liberty, potassæ dissolve them. The floating masses disappear by which becomes the source of the natural acidity of the urine. heat, contrary to albumen. When it becomes turbid from a The very small proportion of soda combines with uric acid, drop of nitric acid, the microscope will show crystals of uric forming urate of soda. acid. A drop of urine containing urate of ammonia, examined on glass by the microscope, shows an amorphous powder, composed of myriads of minute globules; but add a drop of hydrochloric acid, the muddiness disappears, and crystals of uric acid will be seen, the ammonia having deserted the urate to combine with the acid. The colour of urate of ammonia is always owing to its union with purpurine. It is quite white when pure. Ammonia-phosphate of magnesia, or triple phosphate, and the phosphate of lime, are nearly insoluble in water, unless it contains a very small proportion of any acid, or hydrochlorate of ammonia; consequently, in healthy urine these earthy phosphates are held in solution by the phosphoric acid. This urine is generally pale, wheylike, plentiful, and of low specific gravity, 1.005 to 1.015. When the urine is alkaline from disease, these salts deposit, and are always In examining numerous large deposits of urate of ammonia white, unless coloured with blood. They are soluble in weak under the microscope, I have always found, on the addition hydrochloric acid, and insoluble in ammonia and liquor poof weak nitric acid, an appearance of globules so like pus, but tassa. Heat agglomerates the deposit into masses, but promore coloured, that I cannot avoid mentioning it particularly, duces no other change. By adding a small quantity of amfor I have never seen it named by any author; and it is so monia to urine containing any earthy salts, deposits of triple constant in its appearance, that I am led to conclude it de- phosphates take place, which, under the microscope, are seen pends on some chemical combination of the animal matter of either in minute white triangular prisms, stellæ or acicular the urea with the nitrogen of the nitric acid. prisms, or foliaceous crystals, and are very easily detected. These disappear on adding a drop of any acid. When the urine is alkaline these deposits are abundant. Urate of soda.-Very rare, except in gouty diathesis, and fever treated by carbonate of soda. Heat does not dissolve the deposit so quickly as it does urate of ammonia. Uric oxide, xanthic oxide.-Very rare, supposed to have some connexion with the yellow colouring matter of the urine, (hæmaphaein.) It resembles uric acid if noticed inattentively. Colour is salmon or cinnamon tint, not so red as uric acid. The deposit caused by uric oxide is a grey powder to the naked eye, but under the microscope resembles small particles of yellow wax. It is insoluble in solution of carbonate of potass, whereas uric acid is soluble. Ignited in a tube, it does not yield urea, and uric acid does. Phosphate of lime is never found in crystals. It is a very opaque sediment, and a drop examined by the microscope between plates of glass, appears white by reflected, and yellow or brown by transmitted light. and blood, nothing but their appearance under the microscope To distinguish the deposits of the triple phosphates from pus can be depended upon. From mucus, add hydrochloric acid, which will dissolve the phosphates, but not the mucus. From albumen add nitric acid, which dissolves the phosphates, but deposits the albumen. Carbonate of lime is sometimes met with as a deposit in alkaline urine. It is formed from the decomposition of phosTo discover it, phate of lime by the carbonate of ammonia. aware of. COLOURING MATTERS. Cystine. This is very rare, and contains 26 parts in 100 of sulphur. This urine looks like diabetic urine, but it is of a very low specific gravity. It smells of sweet briar when fresh, but soon putrefies, and evolves sulphuretted hydrogen. It is usually found in scrofulous habits. Cystine forms a de- wash the deposit well with water, which dissolves the carposit like the pale variety of urate of ammonia; but, unlike bonate of ammonia, and add any dilute acid, which will disthat deposit, it is unaffected by heat, and it very slowly dis-solve the carbonate of lime with effervescence. Examined solves on the addition of nitric or hydrochloric acids. It is by the microscope, they appear beautiful small transparent soluble in the mineral, and insoluble in the vegetable acids. spheres, like globules of glass, and strongly refract light. Soluble in ammonia, the fixed alkalies and their carbonates, Silicic acid has very rarely been found as a deposit in urine, but insoluble in carbonate of ammonia. By heating on plabut it is often used by impostors, which it is necessary to be tinum foil, it burns with a disagreeable odour. An evaporated solution of cystine in ammonia under the microscope, crystallizes in six-sided laminæ very distinct. It requires Purpurine.-This is a substance of great consequence to caution to distinguish this from chloride of sodium in urine, become acquainted with, as its presence always indicates sewhich naturally crystallizes in cubes, but when combined rious functional or organic mischief in some of the organs with urea assumes an octahedral shape. The ammoniacal connected with the portal circulation. It has been considered solution stains a white-glass bottle black, from the combina- as the same substance as purpurate of ammonia, or the mution of the sulphur of the cystine with the lead of the glass. rexid of Liebig; but Dr. G. Bird has clearly proved it to be Oxalate of Lime.-This salt was considered very rare in a substance sui generis. Purpurine is quite soluble in alcothe urine, but Dr. Golding Bird has proved, in his lectures hol; purpurate of ammonia is insoluble. It always combines in the Medical Gazette, that it is even more common than with urate of ammonia, causing that deposit to vary in tint the earthy phosphates. The urine is acid, has a naturally from a mere flesh colour to the deepest carmine, and is often healthy appearance, the specific gravity from 1.015 to 1.025, mistaken for blood. To distinguish it, dissolve the purpurine generally with some epithelial scales, and always with a in alcohol, examine the rest under the microscope, and the ablarge quantity of urea, uric acid, or urates. To discover the sence of blood-discs will prove it. Of course, the appearance oxalate of lime, set aside the chylous urine for many hours in under the microscope is that of amorphous red urate of ama glass vessel; decant the upper eight-tenths of it; pour a monia. If a small quantity is suspected, add hydrochloric little of the bottom into a watch-glass, warm it, and the oxa-acid to the warmed urine, and a colour, varying from lilac to late will fall to the bottom; remove the top part of the fluid purple, will immediately be produced, if purpurine be present. with a pipette, and under the microscope we find the beauti-By evaporating urine containing it to a syrup, and digesting ful transparent octahedral crystals of oxalate of lime; collect it in alcohol, we obtain a purple tincture, which colour is and ignite the crystals on platinum foil, oxalic acid is decom-heightened by acids and diminished by alkalies. The speposed, and carbonate of lime left, which dissolves in dilute cific gravity of urine containing this substance varies from nitric acid, with effervescence. These crystals are unaltered 1.015 to 1.030; it is not altered in colour by boiling; nitric by boiling in acetic acid, or solution of potass. They dissolve acid added to it often produces a copious deposit of uric acid, without effervescence in nitric acid. loften mistaken for albumen. |