CHEMISTRY. 



Ill 



emerald green, and Pannetier's green ; green ultra- 

 marine (anhydrous chromic oxide), Leune and Cas- 

 telhaz's green (hydrated chromic oxide), Arnaudon's 

 green (chromic metaphosphate ?), Matthieu Plessy's 

 green (phosphate), leave little to be desired in point 

 of beauty, and are free from injurious properties, 

 but are too expensive to compete with the arsenical 

 greens. I propose, in their stead, to calcine strongly 

 an intimate mixture of one part of bichromate of pot- 

 ash and three parts of baked gypsum, of the variety 

 commonly known as scagliola. The result is a 

 grass-green mass, which, on boiling with water, or 

 mixing with dilute hydrochloric acid, leaves a fine 

 powder of an intense and beautiful green, and pos- 

 sessing a very high coloring power. 



Action of Saline Solutions on Tin. Mr. 

 Edward J. Hallock publishes in the American 

 Chemist an account of some recent investiga- 

 tions of his own on the action of neutral sa- 

 line solutions on tin. His first experiment was 

 made with a saturated solution of commercial 

 sodic chloride. A piece of block-tin, free from 

 lead, was placed in the solution April 7, 1875, 

 and on May 6th, the solution meantime having 

 acquired a turbid, milky appearance, it gave a 

 distinct and characteristic reaction for tin with 

 the gold test. It was again tested on July 2d, 

 and the reaction found still more marked. A 

 similar experiment with granulated tin gave 

 similar results. 



Two experiments with saturated solutions 

 of calcic chloride gave distinct reactions for 

 tin in twenty days with the gold test. An 

 experiment with a solution of fused ammonic 

 nitrate showed that this salt attacked the tin 

 more quickly than any other tested, yielding 

 the tin-reaction in four days. 



Solution of ammonic chloride gave only a 

 slight reaction for tin, after long exposure. A 

 solution of a mixture of ammonic chloride and 

 potassic nitrite, in equivalent proportions, and 

 holding about one per cent, of ammonic ni- 

 trate, gave a very faint reaction for tin at the 

 end of fifteen days. A solution of artificially- 

 prepared calcic bicarbonate also showed but a 

 faint trace of tin at the end of two months. 

 Block-tin placed in a solution of calcic sulphate 

 soon became covered with an incrustation, and 

 was unacted upon. 



Formation of Nitrogen Compounds in Na- 

 ture. Hotv nitric acid, and other oxygen com- 

 pounds of nitrogen, can be formed in Nature, 

 is a question that has been lately studied by 

 Prof. Carius, who has contributed a memoir on 

 the subject to Liebig's Annalen der Chemie. 

 It has been asserted that oxides of nitrogen 

 may be produced by oxidation of atmospheric 

 nitrogen through the agency of ozone, but the 

 results of the author's experiments are di- 

 rectly opposed to such a conclusion, and appear 

 to show that free nitrogen remains unacted on 

 in the presence of this active oxygen. Nor 

 does Prof. Carius find that nitrate of ammonia 

 is formed, as Schonbein asserted, by the evap- 

 oration and condensation of water in air. The 

 author believes that the most important reac- 

 tion in Nature by which nitrates and nitrites 

 are generated is the oxidation of ammonia by 



means of ozone ; in this case nitrite of ammo- 

 nia and peroxide of hydrogen are simultane- 

 ously formed, and the nitrite may then be oxi- 

 dized to the state of a nitrate by the action of 

 the peroxide. 



Atmospheric Peroxide of Hydrogen. The 

 results of some late experiments by Schone, 

 made to determine the proportions of peroxide 

 of hydrogen existing in the atmosphere under 

 varying conditions, and the amounts carried 

 down by rain, snow, etc., are thus summed up 

 in the American Journal of Science and Arts : 



Between the first of July and the first of Decem- 

 ber, 1874, Schone examined one hundred and thirty 

 specimens of rain, and twenty-nine specimens of 

 snow, for hydrogen peroxide. These experiments 

 were made in the vicinity of Moscow. Of the whole 

 number of specimens of rain, only four failed to re- 

 spond to .the test, though, out of the twenty-nine 

 specimens of snow, twelve gave no reaction. Hav- 

 ing 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 nail ; (2.) Eelation to other 

 meteoric phenomena, to time of day and to season 

 of the year; (3 ; ) Eelation to the ozone of the atmos- 

 phere ; (4.) How produced in the air ; (5.) Part played 

 by it geologically and botanically ; (6.) Action upon 

 the animal economy when breathed; and (7.) Hy- 



gienic importance. For this purpose, all the rain, 

 ail, snow, dew, and frost, were collected and tested 

 for hydrogen peroxide, the analysis being quantita- 

 tive when possible. Further at various times, espe- 

 cially in clear weather, artificial dew and frost were 

 prepared and examined. Careful meteorological rec- 

 ords were kept during the entire interval at the ad- 

 joining observatory. The ozone was determined 

 by a Schonbein's ozonometer. The results show : 

 that the quantity of hydrogen peroxide in rain varies 

 from 0.04 to 1.00 milligramme per litre ; 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 sol- 

 stice 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 221 litres of rain which fell upon each 

 square metre was only 62.9 milligrammes. In snow 

 there was only 0.05 mgr. peroxide to the litre, the 

 amount diminishing toward the winter solstice. Nat- 

 ural 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 0.05 mgr. per litre, reaching on 

 a bright moonlight night in summer 0.09 mgr. 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 in the month of Au- 

 gust. The amount is greater the higher the temper- 

 ature, 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 litre. He also be- 

 lieves that sunlight plays an important part in its 

 production 



Chemical Changes attending the Growth and 

 Ripening of Fruits. The following, taken 



