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 re-. sorcin. 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 had placed in his hand 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 out 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

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.

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 estab lished 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 ozonometer. The results show that the quantity of hydrogen peroxide in 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

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.

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 heat 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

calcium carbonate, filtered, and treated with an equal volume of alcohol. After twelve hours the greater part of the calcium salt had completely separated. At first the author supposed this to be calcium glycerate in a pure form; but by solution in warm water it left a residue, which only dissolved by long boiling. This residue, about a tenth part of the entire salt in amount, was filtered off, washed, and dried. It appeared as a white powder, non-crystalline. Upon analysis this powder gave numbers agreeing very closely with calcium tartronate. Conversion into the acid confirmed this supposition. Under the glass the acid crystallized in tables having the form of the tartronic acid from nitro-tartaric acid. This view was confirmed by the results of its elementary analysis.-35 C, VIII., 1456, Nov., 1875.

ACTION OF WEAK ACIDS ON SALTS OF STRONGER ONES.

The importance in chemical dynamics of the question, What is the condition in which several substances exist when in solution? has been oftener recognized than experimentally investigated. Bergmann advanced long ago the theory that is now generally maintained, i. e., that universally bodies combined according to the strength of their chemism. Berthollet, on the other hand, asserted that when different salts were dissolved together, as many bodies were formed as by the exchange of acids and bases were possible. Among the experiments made to settle the question, those of Bettendorff are perhaps the most satisfactory. By studying the action of light on certain solutions, he was led to decide for the view of Bergmann. Hübner and Wiesinger, not regarding these experiments of Bettendorff as sufficiently numerous or comprehensive, have made use of a different method for solving the problem by making the distinct proposition: Can a dissolved acid expel a stronger one from its salts in solution without any substance separating from the solution? For these experiments they used benzoic acid for the weaker and nitrobenzoic acid for the stronger acid. They are both monobasic, are easily obtained pure, are easily separated from each other and from their salts, and can be recognized with certainty. They differ only apparently in the strength of their chemism. In the qualitative experiments, barium nitrobenzoate and free benzoic acid were dissolved

in a large excess of water, the solution being heated to 80° Centigrade. After cooling to 14°-17°, the solution contained not only the substances originally dissolved, but also free nitrobenzoic acid and barium benzoate. The nitrobenzoic acid set free in the reaction, together with the benzoic acid also present, was dissolved by agitation with chloroform or benzene, in which the barium salt is insoluble. In the residue, after the solvent was distilled off, the presence of nitrobenzoic acid was proved by means of sodium. In a quantitative experiment, 1.6592 grammes of pure barium nitrobenzoate was mixed with the theoretical quantity 1.1815 grammes of pure benzoic acid, and dissolved in an excess of hot water. The nitrobenzoic acid obtained from the solution was 0.2341 grammes, being 19.81 per cent. of the whole quantity. Additional experiments seem to show that the quantity of the stronger acid set free depends on that of the weaker.-35 C, VIII., 466, April, 1875.

COPPER IN THE HUMAN BODY.

Not long since, in a case of suspected poisoning by a salt of copper, upon analysis a large percentage of metallic copper was found in the liver and kidneys. Subsequent research, however, proved that copper usually exists as a normal constituent of the animal body, the investigation having taken place upon fourteen human subjects from the French hospitals. Portions of these were first dried, then carbonized, and the ashes treated for copper, the amount of which varied in quantity from 7 to 1 milligrammes. The same metal has even been found in the liver of the human fœtus.-13 B, Feb. 20, 1875, 186.

RELATIVE AMOUNTS OF POTASH AND SODA IN MILK AND OTHER FOOD, AND IN THE ENTIRE BODY.

In pursuing the investigation of the value of salt in nutrition, Bunge was led to determine the amount of the alkalies and of chlorine in the most important articles of food, especially in milk; and, in this connection, the amounts of the alkalies and of chlorine in the entire bodies of a number of animals was also ascertained. Besides analyses of human milk, and of that of herbivorous and carnivorous animals, analyses were also made of the entire bodies of a mouse,