14

New Form of Magneto-Electric Machine.

sition, it could hardly be referred to chemical action, but must result from direct stimulation of the sensory apparatus. He thought a glimpse might thus be obtained of some correlation between the modus operandi of hearing and sight and that of taste. In the first case, a supplementary and automatic sensation, in the second the effect of a metallic solution, both entirely subjective, were excited, without the presence of any vapid substance. It seemed possible that both were due to molecular motion, as, indeed, had long ago been held with regard to smell; and that, perhaps, ultimately all the intermediate senses might be found to occupy positions in the gamut of vibration between the last cognisable by the ear and the first by the eye, or rather by the touch in the form of heat.

Mr. ROBERTS mentioned an instance in which sudden danger had been followed by the peculiar taste which results from the introduction of two coins into the mouth, to which allusion has already been made.

Professor FOSTER thanked Dr. Stone in the name of the Society, and expressed a hope that he would continue his suggestive and important experiments.

PROF. G. C. FOSTER called attention to the work of Prof. Everett on the Centimetre-Gramme Second (C.G.S.) | system of units, which will shortly be published by the Society. It is designed to facilitate the study of the quantitative relations between the different departments of physical science by the adoption of a common system of hints. Prof. Foster explained that a committee of the British Association, which was appointed in 1872, and of which Prof. Everett was secretary, recommended the adoption of this system, based upon the metric system. The unit of mass being the gramme, that of length the centimetre, and that of time the second. They recommended that the unit of force be called a dyne, which therefore, is the force required to act upon a gramme of matter for a second to generate a velocity of a centimetre per second. The unit of work is called an erg, and is the amount of work done by a dyne working through the distance of a centimetre. Prof. Everett's book consists of a collection of physical data, reduced to these fundamental terms, so that no other physical magnitudes enter into the expressions, and it cannot fail to prove of the greatest possible value to Physicists.

Prof. Foster then left the chair, which was taken by

Dr. Stone.

Dr. W. M. WATTS communicated a paper on "A New Form of Micrometer for Use in Spectroscopic Analysis." In determining the position of lines in a spectrum by the use of a micrometer eyepiece or divided arc, it is often difficult to see the cross wires distinctly without admitting extraneous light, which, with faint spectra, frequently cannot be done. Dr. Watts has sought to overcome this difficulty by substituting some one known line of the spectrum itself for the cross wires, and to measure the positions of unknown lines by bringing this index line successively into coincidence with them. Thus, for example, the sodium line, which is present in nearly every spectrum whether it is wanted or not, may be made to move slowly along under the spectrum, and the displacement necessary to make it coincide with the lines to be measured may be determined by the readings of a micrometer screw. To accomplish this a convex lens of about 2 ft. focus is placed in front of the prism of the spectroscope, between the prism and observing telescope, and is divided along a line at right angles to the refracting edge of the prism. One half of the lens is fixed, the other half is made to slide over it by means of a micrometer screw. When the movable half of the lens is in its normal position, the only effect is to alter the focus of the telescope slightly, but when it is made to slide over the fixed half, the refraction of the prism is increased or diminished, and half of the spectrum appears to move over the other half, and the sodium line or any other convenient line of reference can be brought into coincidence with the lines to be measured. The indications of this instrument are reduced to wavelengths by means of a series of interpolation curves from

{CHEMICAL NEWS,

the data obtained by observations of the solar spectrum' the co-ordinates of which are wave-lengths and micrometer readings. The author considers the advantages of the instrument to be (1) great precision in results and (2) convenience in use. In illustration of the former quality he quotes 20 readings of the point at which there is coincidence of the lenses. They are remarkably concordant, the mean being 8:34, while the two extreme readings are 8.21 and 8:41.

Prof. GUTHRIE then read a paper "On the Fundamental Water-waves in Cylindrical Vessels." He stated that many attempts had been made to connect wave lengths with wave amplitude, and that the most successful of these were by the Brothers Weber, who allowed a column of water to fall into one end of a long trough filled with water; and they ascertained by means of a stop-watch when the crest of the wave reached the other end. Dr. Guthrie has recently made some experiments on this subject in which he employed a series of five vessels, varying in diameter from 5'5 to 23.5 inches. The water in each was agitated in the centre by a disc of wood, by which means the vessel was made to give what Dr. Guthrie called its "fundamental note." He counted the number of times the wave rose in the centre in a minute and he found that amplitude has no influence upon the rate. It should also be observed that the wave effect is not the same as if the field were of infinite extent. The following are the results he obtained :

Diameter of
Vessel.

I.

23'5 ins.

2.

17.87

3.

14'5

4.

12.5

5.

5'5"

No. of Pulsations

per minute.

106'5

122'7

136.0

146.5

219 0

From which he deduced the curious result that a constant quantity (517'5) is obtained by multiplying the square root of the diameter by the number of pulsations. The question of depth was also carefully considered, and it was ascertained that the number of waves increases slightly with the depth.

Mr. S. C. TISLEY read a paper on a "New Form of Magneto-Electric Machine." After briefly describing the machines which have hitherto been devised, he stated that the new apparatus consists essentially of an electro-magnet with shoes forming a groove, in which a Siemens' armature is made to revolve. It differs from the original machines made by Siemens and Wheatstone in the commutator, as two springs conduct the current from the cylindrical insulator, to which are attached three pieces of metal, one surrounding it for three quarters of its circumference, the second for one quarter, and between these is a third ring insulated and connected with the insulated end of the wire from the armature, and bearing two pieces of metal which are so arranged as to complete the circles of the outer pieces of metal. The armature is so constructed that a stream of water may be constantly passed through it.

A small machine constructed on this principle which, without its driving gear, weighs 26-lbs., is capable of raising 8 inches of platinum wire 8 inches long and 0'005 inch in diameter to a red heat.

The meetings of the Society were then adjourned until November.

Method of Discovering the presence of Nitrous and of Nitric Acids in Water.-Hermann Kaemmerer.— The author adds first acetic acid and a solution of starch in iodide of potassium. If the water turns blue, nitrous acid is present. If it remains colourless, add a few drops of sulphuric acid. A blue colouration which darkens rapidly proves the simultaneous presence of nitrates and of easily decomposable organic matter.-Moniteur Scientifique.

SOCIETY OF PUBLIC ANALYSTS.

poisoning by opium, the acid is precipitated by means of acetate of lead. The meconate of lead obtained is next decomposed by means of sulphuric acid or sulphuretted hydrogen, and the solution thus obtained is tested for meconic acid by means of perchloride of iron. It will now be obvious that this method is open to grave objections.

INFLUENCE OF PHOSPHORIC AND OXALIC
ACIDS ON THE COLOUR OF
SULPHOCYANIDE AND MECONATE OF IRON. The organic liquids to be tested will almost always con-

By A. DUPRÉ, Ph.D., F.R.S.

DURING the discussion on Mr. Young's paper, "On the Volumetric Estimation of Chlorides, &c.," I took occasion to describe, shortly, Volhard's* admirable method for the estimation of silver and of chlorides in an acid solution. Volhard uses sulphocyanide of potassium as the precipitant, and takes persulphate of iron as the indicator. I stated, at the same time, that I had found the presence of phosphates interfered somewhat with the beauty of the reaction. I have since examined this point a little more closely, and believe that the results are not without some interest. The effect of oxalic acid on the red colour of the sulphocyanide of iron, viz., that of destroying it, is already known, but I am not aware that the other effects about to be described have previously been noticed.

If, to a dilute and moderately acid solution of a persalt of iron, we add an equivalent proportion of a sulphocyanide, the well-known blood-red colouration is, of course, obtained. On now adding a solution of either a phosphate, pyrophosphate, or metaphosphate, or of the respective acids, the red colour may be entirely destroyed, even by the addition of comparatively small amounts of these substances. The influence of ordinary phosphates is least, the nature of the base exerting apparently no influence; pyrophosphates are more powerful; and, lastly, metaphosphates are most powerful of all. The effect of metaphosphoric acid I have found to be about five times more powerful than that of corrosive sublimate; unfortunately, it destroys the colour of the meconate as well. If not more of these substances than just sufficient for the destruction of the red colour has been added, the red colouration may, to a slight degree, be restored by the addition of either more acid or more sulphocyanide; but even the addition of a large excess of one of these has, comparatively speaking, but little influence. On the other hand, the addition of more per-salt of iron brings back the colour much more readily, and, indeed, a large excess of iron salt almost restores it to its original intensity.

tain phosphoric acid, which will, of course, be obtained, together with the meconic acid, and may entirely prevent the action of the iron test if traces of meconic acid only are present, as will usually be the case. Fortunately, it is only ordinary phosphoric acid which is likely to be met with in such cases; nevertheless, it is, I think, extremely advisable to remove the phosphoric acid before testing for meconic acid. Oxalic acid, if present, would, like the phosphoric acid, be obtained together with the meconic acid, and would, like this acid, prevent the proper action

of the iron test.

In the cases of pyro- or meta-phosphoric acid, the above reaction can be shown conveniently in somewhat dilute solutions only, since both these acids yield, with per-salts of iron, precipitates which are much less soluble in acids than the ordinary tribasic phosphate.

CORRESPONDENCE.

DOUBTFUL MINERALS, &c.

To the Editor of the Chemical News. SIR,-" Fortunately, anywhere, cats may look at kings." In my last communication, I promised to be more concise. I cannot, however, keep the promise; for Professor Dana, as you know, has taken me to task. In due courtesy to him, I am obliged to reply to the best of my ability, and the subject does not admit of condensation into chemical formulæ.

It is of the nature of Tar to get more fluent as the weather warms, and, I hope, on this time, not to offend "in criticism, whether from a literary, æsthetic, or scientific point of view."

In the sublimity of simplicity, a Tartar cat looked up at two kings, and the kings in their turn looked down at the cat. One stroked the right way, and called him "good-humoured;" the other the wrong way, and dubbed him "uncivil," creating thus, another provoking instance of the Dual nomenclature, to which I have presumptuously taken objection.

In his letter of April 9th (CHEMICAL NEWS, vol. xxxi., p. 160), Professor Dana writes:"T. A. R. gives me more credit than is my due; and, in an uncivil way, brings me into collision on a point of trifling importance with the excellent mineralogist of the British Museum, Professor Maskelyne."

It follows, from the foregoing, that, in testing for traces of sulphocyanide in liquids containing phosphates, it is necessary, either to remove the phosphoric acid, or else to add a very large excess of iron salt; and as the persulphate of iron is, in acid solutions, perfectly colourless, this latter expedient may generally suffice. I think it not unlikely that the presence of sulphocyanide in saliva has sometimes been overlooked, owing to its also containing phosphoric acid. In his titration, Volhard recommends the addition of a very large excess of iron salt as indicator, since in an acid solution the intensity of colour produced by a given proportion of sulphocyanide is the greater the larger the amount of iron present. In this way, the in-fencing; but before I touch a foil, allow me to premise fluence of any phosphoric acid present is also reduced to a minimum.

Oxalic acid, or oxalates, have also, as has already been noticed, the power of destroying the red colour of the sul phocyanide of iron.

Seeing the strong effect of these acids on the red solution of sulphocyanide of iron, I examined their influence on the similarly-coloured meconate, and found them equally effective in destroying the red colour of the latter. Here, also, meta-phosphoric acid had the greatest effect, next came pyrophosphoric, and, lastly, ordinary phosphoric.

Now, in the ordinary method employed for the detection of meconic acid in organic mixtures, in cases of suspected

* J. Volhard, Journ. fur Prakt. Chem., 1874, ix., p. 217.

To these allegations, in a sort of legal way, I shall plead "Not Guilty, and extenuating circumstances." The venerable Professor's letter challenges a little

that, if I have not already written enough to indicate the high appreciation I entertain of both these learned mineralogists, I am willing to go still further, and in frankness say that I regard them both as of Nature's true nobility. To a very high esteem for both, I add no low degree of reverence for the veteran Dana. Both have earned their titles to honourable distinction. Their titles are "Dana," and "Maskelyne; " names not in the least likely to be taken to mean either the same thing, or any other bodies, and it is my desire that nobody shall have the audacity to turn them into mutilated Greek or hybrid names for "universal use."

Initially and otherwise, perhaps, I may be taken for a very soft thing; but I have a habit of showing my respect to eminent men, and "sisters of mercy," by uncovering my head whenever I meet them. I should

16

Doubtful Minerals.

do this to Dana and Maskelyne, although they would not know me from Adam. Indeed, I half love the Basle people for once having made it a part of the education of every child to take off the hat to Daniel Bernouilli, the mathematician. It is exquisite enjoyment to pay oldfashioned proper respect to respectable people, whether "to greatness born," or not-I mean the truly noble-all those who befriend mankind.

The following are the chief points in Dana's communi

cation:

(1). That I give him more credit than is his due.
(2). That, in an "uncivil" way, I have brought him
into collision on a point of trifling importnce
with Maskelyne.

(3). That the system in mineralogical nomenclature is
not of his making.
(4). That by implication I make out Bendant,
Haidinger, Von Kobell, Nicol, Greg, and
Lettsom, to be "all alike blockheads," because
they have called copper pyrites chalkopyrite.
(5). That, in the adoption of the scientific names of
minerals used in his treatise, he has simply
followed the best authorities, and "the usual
Law of priority."

(6). That the objection urged to names from a Greek
or Latin source, is the old one of " uninformed "
minds against all scientific nomenclature.
(7). That the object secured by such names is
uniformity the world over, through all
languages."

66

(8). That nearly all recent mineralogical authors havé adopted, and that "science has accepted Chalcopyrite for universal use," in lieu of copper pyrites.

Now since the tickle of a feather is always more or less an agreeable irritation, and "the dread and fear of kings" not being heavy on me, I propose to stick closely to the subject in hand, and, careless alike of praise or blame, plainly say what I think upon it in this reply.

In the first place, Dana heads his letter "Doubtful Minerals," and says not a word about them afterwards. About "Dual nomenclature" he scarcely touches the fringe of the argument: yet, what he has written, he has written, and, from his writing, I take the diploma of a kind of "excellent," bestowed on Maskelyne as strengthening mixture for my defence.

or "

Dana dexterously touches my hamstring, and has a little the best of me, in one respect, in the wrestle about the fair fame of chalcopyrite. Had I selected "Halite" Sphalerite," for my figure of speech, possibly he would not have written at all; therefore I may goodhumouredly chuckle over the fact that my experimental cablegram has been the means of bringing the two mineralogical kings into verbal, and, I hope, not uncivil, collision.

To the enumerated points of Dana's letter I venturously reply:

(1). I cannot give him too much credit for his life of honourable labour.

(2). It is not appropriate to label me "uncivil" in this matter. I cannot bring my mind to consider the subject of Dual mineral nomenclature one of " trifling importance." I hold it still to be the very reverse of "trifling." But, if really trifling, then all scientific bothers should be viewed as trifles, and tangled yarn the delight of

weavers.

CHEMICAL NEWS,
July 9, 1875.

But the goal to which I am agonising is not whether The object I am Dana or Maskelyne's nomenclature is to be, or what other system should be, preferred. feebly aiming at is to get an end put to the present inconvenient diversity of use, and now that I have wired together the only two intelligences that can readily effect this desideratum, I am quite buoyant with expectation and cheerful hope.

(4). I shall be excused for saying that it is scarcely regal to parody the speech of low intelligence, and to put "blockhead" into my hand to hurl at Bendant, Nicol, and others my superiors. I never could apply the damaging epithet to them, for all in their turn, as well as Dana, have instructed me.

66

It is fact that the authors cited by Dana used chalcopyrite for copper pyrites; but, it is also fact that copper pyrites was the expression used by Allan, Jameson, Dictionary," in the recent Chapman, Thomson, Phillips, Gmelin, Bischoff, in Ure's Dictionary," in Watts's " mineralogical offshoots from Jermyn Street (of Ramsay, Rudler, and Jordan), by Maskelyne at the British Museum, and mirabile dictu by Dana himself prior to 1868!

I am too far off the British Museum Library, or I would ascertain by what name Dana called copper pyrites in the first, second, third, and fourth editions of his "System of Mineralogy." It is sufficient, however, "Manual of state that in his for my purpose to Mineralogy," 1863 and 1867, he uses copper pyrites always, and chalcopyrite never!

In 1725, Dana's authority, Henckel, calied copper pyrites, pyrites flavus, although he also appears to have suggested that the adjective flavus should be put into Greek, as brass. xaλkos was thus made to depose flavus erroneous idea It will not be denied that both pyrites unnecessarily, and withal to carry an along with it. flavus, and copper pyrites, have the appreciative merit of A student can seize and hold vivid directness of expression, which chalkopyrite has not and never can have. forceps-like, the idea involved in them; but not so in I do not say that chalkopyrite. A Folkestone man might feel inclined to It would appear as useless to contend take the latter for pyrites o' th' chalk. he would do so. for the appropriateness of chalcopyrite, as of that hybrid "gold-brass," aurichalcite.

(5). I am entitled to ask who are the best mineralogical authorities of the past? and who instituted the law of priority? This law of priority upon which Dana lays such peculiar stress, is evidently unlike the law of the In 1868 he rejects the Medes and Persians, for Dana himself is not very rigid in his adherence toi t.

Augite of Wern, 1792, for Pyroxene of Häuy, 1801. Hornblende of Wern, 1789, for Amphibole of Häuy, 1801.

Steatite of Kirn, 1794, for Saponite of Svanberg, 1840.
Mispickel of 1747, for Arsenopyrite of Glock, 1847.
Meerschaum of Wern, 1788, for Sepiolite of Glock,
1847.

Anatase of Hauy, 1801, for Octahedrite of Wern, 1803.
Pitchblende of old, for Uraninite of Dana, 1868.
Tin Pyrites of Kirn, 1797, for Stannite of Dana, 1868.
Blende of old, for Sphalerite of Glock, 1847.
Galena of Pliny, for Galenite of v. Kob., 1858.
Mimetesite of Breith., 1841, for Mimetite of Haid., 1845.
Berzelite of Levy, 1837, for Mendipite of Glock, 1839.
Rock Salt of old, for Halite of Dana, 1868.
Tungstic Ochre of B. Silliman, 1822, for Tungstite of
"Dana, 1868.

(3). I have not hinted anywhere that Dana is "the author of the system in mineralogical nomenclature: for literally there is in it really no system at all.

The total want of system is simply discreditable to the scientific age we live in, and to the whole body of its mineralogists. I do not, however, hesitate to declare openly that my venerated teacher has been the author of a good deal of the present "confusion of tongues" in mineralogical nomenclature, his laborious efforts to the contrary, notwithstanding.

Sulphuric Acid of old, for Sulphatite of Dana, 1868. Nickeline of Bend., 1832, for Niccolite of Dana, 1868. Delvauxene of v. Hauer, 1854, for Borickite of Dana, 1868.

The transmutations of horn silver are interesting. It became Kerargyre under Bend., 1832; Kerat under Haid., 1845; Argyroceratite under Glock, 1847; Kerargyrite afterwards, under Dana, and Chlorargyrite (as now)

under Maskelyne. In 1868 Dana put forth Ketarargyrite | able ground of objection against the wholesale alterations as the proper derivative, changed the Greek & into c, and let go the word Cerargyrite for "universal use." I may here remark that Dana has not always been faithful to his own decisions, e.g., the Sylvanit of Neck., 1835, was changed by Dana in 1837 to Aurotellurite, and reinstated as Sylvan.te in 1868. Emplektite of Kenng., 1853, was made Tannerite, 1854, and Emplectite, 1868. Feuerblende of Breith., 1832, made Fireblende, 1850, and Pyrostilpnite, 1868. Plumbo-gummite of Shep., 1835, made plumbo-resinite, 1837, and again plumbo-gummite, 1868. Melinophane of Scheerer, 1852, made Meliphane by Dana, 1867, and changed for Meliphanite, 1868.

(6). Here Dana does me injustice. It would indeed be absurd to object to appropriate scientific names from a Greek or Latin source. I have never made such an objection, and I hope I shall not live to make myself half so ridiculous. Ardent lovers of such names can flounder about in paleontology to their hearts' content, or other-versal adoption." wise.

The stand I make for the retention of Common Salt, Blende, Copper Pyrites, Amber, &c., is precisely for the reason assigned by Dana for his retention of Quartz, Diamond, Garnet, Gypsum, Realgar, Orpiment, &c., namely, that these words have become part of general literature, and, more or less, this may be made reason

Chemical Notices from Foreign Sources.

rite, Keramohalite, Kühnite, Laumonite, Lettsomite, Lievrite, Meer; CHEMICAL NOTICES FROM FOREIGN