Imagini ale paginilor
PDF
ePub

which these bodies take their name, they can therefore fix directly the elements of water and form monobasic acids; dimethylene carbonyle uniting with water directly and yielding propionic acid. Moreover, by virtue of this unsaturation they can unite directly with three atoms of oxygen to form dibasic acids; camphor yielding camphoric acid in this way. Conversely, the removal of water and carbonic dioxide from a single molecule of a dibasic acid yields a carbonyle; thus differing from the analogous production of ketones, by the fact that in the latter case the removal is from two molecules of a monobasic acid. The author gives evidence to show that camphor belongs to this class of bodies, and says that, had he not hesitated to found a new class of bodies on a single compound, he would have proposed camphor as a carbonyle long ago.-Bulletin de la Société Chimique de Paris, II., xxiii., 146, February, 1875.

HÆMATIN NOT FERRUGINOUS. It has been for some time known that the proportion of iron which existed in the coloring matter of the blood, called hæmatin, was very variable, and that by repeated purification it could be so far reduced in amount that only a trace remained. Hence the opinion has arisen that the iron is not an essential constituent, as is generally supposed. Paquelin and Jolly have examined the question at length, starting from the well-known researches of Chevreul upon this substance, which were to the same purport.

The results have shown the correctness of the assumption, they having succeeded in devising a process by which the whole of the iron may be removed and the hæmatin obtained pure. In brief their method is as follows: Having removed the albuminates of the blood by basic lead acetate, the corpuscles are dried and powdered, then digested in glacial acetic acid until they are reduced to a gelatinous mass. The coloring matter is then taken up by carbon disulphide or benzene, and the hæmatin recovered by careful evaporation of the solvent. The corpuscles may with advantage be macerated in alcohol containing ten per cent. of ammonia previous to the treatment with acetic acid. The purification of the hæmatin from the iron is the next step. It is dissolved in ten times its weight of acetic acid, two and a half parts of citric acid dissolved in a little water is added, and the whole is brought to boiling to favor the colution of the iron. To the cooled liquid, ammonia is added in quantity sufficient to exactly neutralize the acids, and the precipitated bæmatin allowed to subside. This treatment is repeated so long as ammonium sulphide discovers in the supernatant ammoniacal liquid any trace of iron. The purified hæmatin is finally dissolved in ether, the solution filtered, and the ethereal liquid allowed to evaporate spontaneously. The pure coloring matter is insoluble in water, slightly soluble in alcohol, but readily so in ether, chloroform, carbon disulphide, and benzene. It burns on platinum like a resinous substance, without leaving any trace of ash.–6 B, LXXIX., 918.

[merged small][merged small][ocr errors][merged small][ocr errors][ocr errors][ocr errors][ocr errors][merged small][ocr errors]

FORMATION OF SULPHATES BY GAS FLAMES. A white incrustation is always formed after a short time on the glass covers hung over gas flames. This incrustation consists of small crystals of normal ammonium sulphate, with a trace of soda and potash. The sulphur in the gas which is burned to produce the sulphuric acid does not exist in the condition of hydrogen sulphide, but in that of carbon disulphide. The ammonia is not a product of combustion, for if à basin whose lower surface is moistened with hydrochloric acid be held over a gas flame, there are no fumes visible, and no ammonia is found even with the delicate reagent of Nessler. But unburned gas contains a small quantity of ammonia, enough to give a yellow color with the Nessler test. Priwoznick has investigated this question, and supposes that the ammonia comes from the nitrogen of the air, for Saussure has shown that ammonia is formed when hydrogen is burned in oxygen containing nitrogen. Schönbein proved the presence of ammonium nitrate in the products of combustion of fat and of coal-gas. The carbon disulphide in the gas would burn to carbonic and sulphurous dioxides. But sulphurous oxide can not exist in presence of ammonium nitrite, but is immediately oxidized to sulphuric acid and combines with the ammonia. The glass cylinder of an argand lamp is also often covered with a white incrustation. This consists mainly of potash, soda, lime, etc., from the ash of particles of dust in the air. -14 C, CCXIII., 223.

[ocr errors][ocr errors][ocr errors][merged small][ocr errors][ocr errors][merged small][ocr errors][merged small][ocr errors][ocr errors]
[ocr errors][ocr errors][ocr errors][ocr errors]

ON A NEW COLORING MATTER CALLED EOSIN. In 1871 Baeyer observed that when pyrogallol was heated with phthalic oxide under such circumstances that water was abstracted, a peculiar body resulted, which was brownred in color with a yellowish-green lustre, and which dissolved in alkalies with a magnificent blue color. To this substance he gave the name Gallein. A short time afterward he observed that this reaction was entirely general, and that whenever a phenol of any atomicity was heated in this way in presence of a dibasic organic acid, a coloring matter was the result. The body thus obtained gave rise to two derivatives; one of which is its anhydride, and the other its reduction product. For the coloring matter itself Baeyer proposes the termination ein; and for its reduction product, which is colorless, in. Thus with phthalic acid and phenol, for example, there is a phthalin and a phthalein of phenol. Among the various phenols which were thus treated with phthalic oxide was resorcin, one of the three diatomic phenols. Of course the products were a phthalin and a phthalein of resorcin. The phthalein of resorcin was obtained in yellow flocks which dissolved in ammonia, giving a red solution, which had such a magnificent green fluorescence as to secure for it the separate name fluorescein. It would seem as if a coloring matter like this, prepared from substances exceedingly rare, and obtained only in minute quantities by long and tedious chemical processes, could never become an article of commerce. But early in the present year Hofmann bad placed in his band a new coloring matter, which had only a few months before come into practical use. This new coloring substance had the name Eosin, a name given in allusion to the beautiful red color of its aqueous solutions, recalling that of the morning dawn. Upon investigation, eosin turned ont to be a derivative of the remarkable coloring matter which Baeyer had called fluorescin. It was the potassium salt of tetrabrominated fluorescin, or, what is the same thing, of the phthalein of dibrom-resorcin. It is prepared commercially at the Baden Aniline Works, by Caro. Baeyer proposes the following test for it: A portion of the coloring matter is agitated with water and sodium amalgam at a gentle heat. The solution is soon decolorized, the bro

[ocr errors][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors]

mine being removed and colorless fluorescin produced. If now water be added and a few drops of potassium permanganate solution, the fluorescin changes to fluorescein, and the liquid becomes quite green and almost opaque in reflected light.-35 C, VIII., January, 1875.

[ocr errors][ocr errors][ocr errors][ocr errors]

PEROXIDE OF HYDROGEN IN THE ATMOSPHERE, Schöne has made a series of experiments in the vicinity of Moscow to determine the amount of hydrogen peroxide in the atmosphere. Between the 1st of July and the 1st of December, 1874, he examined for this purpose one hundred and thirty specimens of rain and twenty-nine specimens of snow. Of the whole number of specimens of rain, only four failed to respond to the test, though out of the twenty-nine specimens of snow twelve gave no reaction. Having established the fact, the author continued his investigations with reference to the following points: (1) Form of occurrence of hydrogen peroxide in the atmosphere-whether gaseous or dissolved in the fluid or solid rain or hail; (2) relation to other meteoric phenomena, to time of day, and to season of the year; (3) relation to the ozone of the atmosphere; (4) how produced in the air; (5) part played by it geologically and botanically; (6) action upon the animal economy when breathed; and (7) hygienic importance. For this purpose, all the rain, hail, snow, dew, and frost were collected and tested for hydrogen peroxide, the analyses being quantitative when possible. Further, at various times, especially in clear weather, artificial dew and frost were prepared and examined. Careful meteorological records were kept during the entire interval at the adjoining observatory. The ozone was determined with a Schönbein's ożonometer. The results show that the quantity of hydrogen peroxide iu rain varies from 0.04 to 1 milligramme per liter; that the larger the drops the greater the amount; that the first rain after dry weather is poorer in peroxide than that which falls later; that the peroxide is greatest when the wind is south and southwest, that in the rain brought by the equatorial current being greater than that which falls in the rain produced by the conflict of this with the polar current, or brought by the latter current itself; that the relative quantity of peroxide in rain increases from the summer solstice

[merged small][ocr errors][ocr errors][merged small][merged small][merged small][ocr errors][merged small][ocr errors]

el b

[ocr errors][merged small][merged small]

to the autumnal equinox, and then diminishes; that the quantity is not greater in rain which falls during a thunder shower; and that during the four months the absolute quantity of hydrogen peroxide contained in the 221 liters of rain which fell upon each square meter was only 62.9 milligrammes. In snow there was only 0.05 milligramme of peroxide to the liter, the amount diminishing toward the winter solstice. Natural dew and frost contain no peroxide, or at least less than one twenty-five millionth of this substance. In artificial dew and frost the amount of peroxide varied from 0.04 to 0.06 milligramme per liter, reaching on a bright moonlight night in summer 0.09 milligramme. The amount increased with the altitude of the sun. The daily maximum was reached between 12 and 4 o'clock P.M., and the annual maximum in the month of August. The amount is greater the higher the temperature, the clearer the sky, the higher the absolute and the lower the relative humidity of the air. The author concludes that the peroxide is contained in the air both free and in solution, to the extent as a maximum of 0.000000268 c. c. in a liter. He also believes that sunlight plays an important part in its production.-35 C, VII., 1693.

[ocr errors][merged small][ocr errors][ocr errors][merged small][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors]

TARTRONIC ACID A GLYCERINE OXIDATION PRODUCT. Hitherto tartronic acid has only been known as a product of the spontaneous decomposition of nitro-tartaric acid and as a reduction product of mesoxalic acid. Theoretical considerations led Professor Sadtler, of the University of Pennsylvania, to conceive that this acid might be formed by the oxidation of glycerine, and hence to search for its presence in the products of this reaction. For this purpose one part of glycerine was mixed with an equal weight of water, and to this was added about one and a quarter parts of fuming nitric acid. This latter was poured into the vessel through a long funnel tube, so as to form a layer upon the bottom. After about six days the evolution of gas had ceased, and the solution was evaporated at a gentle beat to a sirupy consistence, then diluted, and lead carbonate added in excess. The liquid filtered from the mixed lead oxalate and carbonate gave, upon evaporation, thick crusts of lead glycerate. These, redissolved in water, were freed from lead by hydrogen sulphide, the solution concentrated, neutralized by

t the

و ر ر ر

sonth

turiol

*תון 1

1 at, (1

qui!!

Istice

« ÎnapoiContinuați »