was 3°4 Cent. below the other two, which remained stationary. This experiment proved, that the tin vessels completely cut off the radiation, (even of the lampblack,) and that the polished caps had the same effect. In like manner the radiation of silver was determined by two thermometers capped with that metal-one in a covered, the other in an open vessel, and a third blackened and also in an open vessel. The first showed the temperature of the air, the second the radiation of the silver, and the third that of lampblack. The results of a series of careful observations gave the radiating power of silver 3-026, that of lampblack being 100.-being not far from the recent determination of MM. de la Provostaye and Dessains, by a quite different method. One important precaution to be observed in all these experiments is suggested by M. Melloni, we believe for the first time. We should not experiment except at some distance from the ground and in dry weather-otherwise the instruments soon become bedewed, and the high radiating power of water soon brings them all to the same degree, whatever be the nature of the coating. If the stems are left uncovered, the thermometers are cooled down to the bulb, and the same effect will be noticed. The radiating power of the following substances was obtained by applying them to the caps of the thermometers. The following comparisons were made by placing the substances in a little heap on the bottom of the tin dish, and high enough just to cover the cap of the thermometer. The portion of the sky concerned in the radiation is included within 30° or 35° of the zenith. Even clouds beyond this have but little interfering effect. That radiation takes place not only from the surface but from the parts beneath, was proved by the greater radiation of several coats of varnish than of a single one. This explains a phenomenon which has been brought as an argument against Wells' theory. It is objected that very thin bodies, such as spider webs, should recover their temperature from the air as fast as they lose it by radiation. Hence such substances should not be covered by the dew. But spider webs are notoriously productive of dew. M. Melloni contends that the webs radiate from all portions of their substance, and therefore lose much more than they can receive, in proportion to other bodies. A long continued course of experiment has satisfied M. Melloni, that the amount of radiation is usually stated far too high-that while under certain circumstances some bodies can be cooled to 8° Cent. below the temperature of the air four or five feet above-in general the effect of radiation is to reduce the temperature of vegetation, &c., not more than 2° Cent. below that of the surrounding air. The dampness of the air is such as readily to allow of the deposition of dew with even this small change. Another important conclusion of our author, is a confirmation of the law just announced by Wilson, that the loss of heat from radiation in a calm, clear night, is uniform at all temperatures of the air. The whole of this investigation, while it corrects certain inaccuracies and improves the methods of experiment, in every respect confirms the theory of dew, laid down by Wells. G. C. SCHAEFFER. 2. On the Composition of the Organic Alkalies; by M. AUG. LAURENT, (Ann. de Chim. et de Phys., May, 1847.)-This distinguished chemist has reexamined the vegetable alkalies, since much uncertainty prevailed as to their true formulæ, and as for many of them, formulæ have been received, which according to the views of M. Laurent, cannot represent any chemical compound. The error in most cases arises from the fact, that a difference of 002 to 003 of hydrogen is sufficient to change their constitution. By means of a modification of the usual process for organic analysis, he has found that he can determine the hydrogen to 001. By this process, the following formulæ were established. We give the notation adopted by the author, as a translation to our system would in some cases involve the use of fractions. It is only needful to remember that H, and N2 of the French authors, are H and N with us. 2 C1, H22 N2 O2 C19 H22 N2 19 Quinoleina C, H, N Morphia Lophia Picryle 3 C23 H16 N2 C21 H15 NO2 Starch Pyroxyline Conina 19 H1, NO, CH 10 13 C10 H 10 6 Hemipinate of am. C10 H16 N2 Narcotina C23 H25 NOT Cotarnina C12 H13 NO3 15 G. C. S. 3. Researches on the Chemical Constitution of Asparagine and Aspartic Acid; by M. R. PIRIA, (Ann. de Chim. et de Phys., Feb., 1848, trans. from the Italian.)-The chief results of M. Piria's remarkable discoveries in relation to these substances, have already from time to time appeared in various journals; but we now for the first time find the complete memoir, of which we shall give a brief abstract. Process for obtaining Asparagine.-About 22 pounds of vetches were allowed to germinate in a dark apartment. When the plants were two feet high, they were cut up, the juice expressed and evaporated, after filtration from albumen coagulated by the heat. The almost syrupy liquid deposited an abundant crop of crystals of aspara gine. These were purified by two or three re-crystallizations from boiling water, the last time using animal charcoal. The crystals were of uncommon beauty, not unlike those of sugar candy. Copper vessels impart a blue tint, and sulphuretted hydrogen causes this to disappear. The product of asparagine is 1 per cent. for the vetches used. The same quantity was obtained from the plants germinated in the light; but none from the seeds themselves, nor from the plants when the flowers had formed. The constant acid reaction of the liquid even when concentrated, induced M. Piria to suspect the presence of some foreign acid; but at last he arrived at the conclusion, that the asparagine itself (contrary to all former statements) is really an acid of some power. A saturated solution of asparagine gives when heated with acetate of copper, a rich ultramarine blue precipitate, increasing in quantity on cooling. Its composition is C,(H, Cu)N2 06-that of asparagine free from water of crystallization, C, H, N2 O. The asparagine may be obtained unaltered from this substance, by the use of HS. A similar compound with potassium has been noticed in this Journal for March, 1847, p. 258. 8 Action of Ferments.-Under the influence of an azotised principle in the plants, the impure asparagine in solution, or the juice itself, undergoes fermentation, emitting a putrid odor; and there is found remaining a quantity of succinate of ammonia, formed by the fixation of 2HO+H2. 8 2 8 12 8 Asparagine C, Hg N2 О6+2HO+H2 = C, H12 N2 O, succ. amm. Action of Acids and Alkalies.-It is well known that these agents decompose asparagine into aspartic acid C, H, NO, and ammonia2HO being added. 8 8 It is incorrectly stated that concentrated hydrochloric acid produces a new and more soluble acid. Our author has found that this is only aspartic acid retained in solution by the hydrochloric acid. Even nitric acid when pure, forms only aspartic acid; from the solution under certain circumstances, acetate of lead precipitates a double nitrate and aspartate of lead; which however cannot always be ohtained. The reaction of nitric acid containing hyponitric, was quite remarkable; a large quantity of pure nitrogen was given off, when either the asparagine or aspartic acid was used. The complete decomposition was effected by dissolving in nitric acid, and passing a current of binoxyd of nitrogen until no more nitrogen was disengaged; the acid liquid saturated with carbonate of lime gave with acetate of lead, the well known crystalline and fusible malate of lead. Analysis confirmed this. Hence asparagine is an amid analogous to oxamid, and aspartic acid another corresponding to oxamic acid. Their names should be malamid and malamic acid. M. Piria proved the analogy of this reaction of hyponitric acid upon oxamid, succinamid and butyramid. In all cases nitrogen was giv. en off, and the oxalic or other acid remained in solution. Urea too is transformed, as is well known, into nitrogen and carbonic acid. The remarkable facility of this decomposition, which takes place even in the cold solutions, is strikingly contrasted with the tedious and never definite decomposition of the amids by heating with caustic potash. [The distinctness of the reaction of hyponitric acid with the amids, seems to afford us a means of research of vast promise. Most of the azotised compounds of unknown relation, are undoubtedly amids; their decomposition by means of caustic potash is slow, and always affords a variety of products. With hyponitric acid, we shall only have to make allowance for the oxydation by the nitric acid, which would in some instances take place; but this is in general an easy matter for the oxydation by nitric acid has been well investigated for most of the substances likely to be found.] G. C. S. 4. On the presence of Copper in the Bodies of Animals; by M. DESCHAMPS, (Comptes Rendus, Jan., 1848.)—This metal is constantly present in most of the formations in the vicinity of Paris, and seems to be derived from the decomposition of cupriferous sulphuret of iron. It is taken from the soil by plants, and from them by men and animals. Copper and also lead are received in part from cooking utensils, &c. Soils free from copper soon obtain a portion by manures, &c. Carbonate of ammonia is the means of carrying copper from the soil into plants, and in the azotised compounds of this metal, seems to enter by a replacement similar to that which takes place in certain ammoniacal salts. These are a few of the conclusions drawn by M. Deschamps from his curious investigations. G. C. S. 5. On the presence of Arsenic in certain Chalybeate Waters; by M. AUDOUARD, (Comptes Rendus, Jan., 1848: and by M. FILHOL, Journ. de Pharm. et de Chim., Jan., 1848.)-Both of these authors have proved the existence of arsenic in very minute quantities in chaly beates. The latter found the deposits from springs of the Pyrenees to contain from 0.03 to 0.058 per cent. of arsenic, and sometimes a trace of copper. Both remark that this minute quantity can never give rise to mistakes in case of poisoning. [Can it have any effect upon the medicinal properties of the waters in which it is found?] G. C. S. 6. On a new method of analysis of Inorganic matter in Blood: and on the constant presence of several metals in this fluid; by M. E. MILLON, (Comptes Rendus, Jan., 1848.)-The blood is received in a vessel containing about three volumes of water to one of blood, and introduced into a flask containing chlorine. The organic matter immediately coagulates, changes color and loses all traces of organization. By expressing the clot and washing, the whole inorganic matter is removed and is found in the clear and limpid solution. Not more than one per cent. of organic matter is carried off in solution. The reaction with chlorine is complete in two or three minutes; the separation of the iron in this way is therefore a neat class experiment. The saline ingredients after ignition are examined as usual. Of this residue, 100 parts containSilica, from 1 to 3 Copper, from 1.5 to 2.5 Lead, Magnesia, 20. " 24 ? Experiment shows that these metals, like iron, are found only in the globules. This method of analysis is suggested as suitable for all the fluids, &c. of the animal economy. The most repulsive matters furnish immediately a clear saline solution. G. C. S. 66 1 66 5 66 7. New mode of estimating the Sulphur in Organic Substances; by H. WEIDENBUSCH, (Chem. Gaz., June, 1847, from Lieb. Ann.)— The substance is heated with the strongest nitric acid, and an excess of nitrate of baryta, until all organic matter is destroyed. The mass is dried in a platinum dish at 212°, and then fused, avoiding a deflagration. The fused mass is to be treated with dilute acetic acid, and heated to remove carbonate of baryta. After filtering and washing, a second treatment with acetic acid furnishes the sulphate of baryta perfectly pure. G. C. S. 8. Preparation of pure Barytic Water and Salts of Baryta; by H. WACKENRODER, (Chem. Gaz., July, 1847.)—Mix intimately 240 grms. of finely ground sulphate of baryta, with 60 grms. rosin and 20 grms. powdered charcoal. Heat to redness from half to three quarters of an hour. Salts of baryta are prepared by precipitating the solution of the sulphuret, by carbonate of soda. To obtain the chlorid pure, crude muriatic acid is added to the solu tion of sulphuret to slight excess; the precipitated sulphur, sulphate of baryta, &c., is filtered off, and the solution evaporated nearly to dryness. The impurities remain in the mother-liquid; adhering chlorid of iron is removed by a faint red heat. Barytic water is prepared as usual by oxyd of copper. If this metal is found in the liquid after boiling, a small quantity of recently precipitated hydrated oxyd of silver, or its carbonate, will on digestion, remove the copper and hypo-sulphurous acid. The originality of this process, is in the use of rosin and powdered charcoal instead of meal, and also in a less degree of heat than is usually recommended. About one-third the sulphate is decomposed. The remainder can be used over again. G. C. S. 9. On the Fusion of Rocks; by A. DELESSE, (Jour. de Pharm. et de Chem., Jan., 1848.)-The author has observed that the igneous rocks on fusion undergo a diminution in density, when they cool into a vitrified mass, which is the greater in amount as the rocks contain more of silica and alkali, and less when more iron, lime or alumina are present. As a general rule, the older rocks, as granite, &c., decrease most in density; the order is nearly that of their age down to the most modern volcanic rocks, which undergo but little change. This is of course the reverse of the order of their fusibility. The author suggests that the crystallization of these rocks has decreased the radius of the earth, as a diminution of volume is the inevi table result of crystallization, whether from fusion or aqueous solution. G. C. S. 10. On a new Process for covering different Metals with Brass or Bronze, (Chem. Gaz., May 15, 1848, from Newton's Journal, May, 1848.)-MM. Brunel, Bisson and Gaugain, instead of the cyanids before used, employ a solution in water, composed of 500 parts of carbonate of potash, 20 parts of chlorid of copper, 40 parts of sulphate of zinc, and 250 parts of nitrate of ammonia. In order to obtain bronze, a salt of tin is substituted for the sulphate of zinc. By means of these solutions, wrought or cast iron, steel, lead, zinc, tin, and the alloys of those metals, either with each other or with bismuth and antimony, may with facility be coated with brass or bronze, after being scoured in a suitable manner, according to the nature of the metal. The operation is performed at the ordinary temperature. The article to be coated is put in communication with the negative pole of a Bunsen battery, the positive decomposing pole being a plate of brass or bronze. When large surfaces are to be coated, experience has proved that it is requisite to increase the number of pairs of plates, and not their size. When the articles have been coated, and have undergone the usual coloring process, they equal in beauty the finest bronzes. |