52 Scientific Intelligence. 



slightly inclined, and at about three-fourths of its length, a reser- 

 voir was placed. Beyond this the gas passed through copper 

 tubes which were immersed in a freezing mixture. Upon the 

 main tube was a safety valve which allowed the pressure to be 

 regulated at pleasure ; this was maintained at about 140 pounds 

 to the square inch. In the first experiment, 538 liters of gas were 

 passed through the apparatus, in the second 467 liters, and in the 

 third 12*74 liters. In both reservoirs, 84 c. c. of liquid was ob- 

 tained in the first experiment, 77 c. c. in the second, and 195 c, c. 

 in the third. Of the 77 c. c, 54 c. c. of sp. gr. -690 condensed in 

 the first reservoir (i. e., by pressure alone without cold) and 23 c. c. 

 in the second, of sp. gr. -650. Of the 195 c. c, 114 c. c. of sp. gr. 

 •691 condensed at + 16°, and 81 c. c, of sp. gr. '658, condensed 

 at — 18°. As a mean therefore each liter of gas yielded about -1.08 

 c. c. of liquid of sp. gr. -680 ; which is equivalent to one gallon 

 for each 1000 feet of gas. After this treatment the gas was found 

 to have lost its illuminating power, giving no more light when 

 burned from a bat wing jet than does a Bunsen burner. From 

 this and other facts, the author concluded that ethylene is absent 

 from shale gas. Common coal gas when subjected to this treat- 

 ment gave no appreciable quantity of liquid. The shale products, 

 by weight, therefore, which are obtained on distillation, are :— 

 non-luminous combustible gas 20-9 per cent ; volatile liquids, sp. 

 gr. -680 dissolved as vapors in the gas 4-9 per cent; commercial 

 paraffins, sp. gr. •700--800, 52-3 per cent ; tarry acid or basic bod- 

 ies 21*9 per cent. The author proposes a method for commer- 

 cially preparing these light oils from the ^as. — J. Chem. Soc, II, 

 xiii, 856, Sept., 1875. ~" G. f. b. 



3. On the Medico-legal determination of Arsenic. — Having occa- 

 sion to revise, for purposes of physiological investigation, the 

 methods ordinarily employed for the detection of arsenic hi the 



quantitative exactness. He thereupon devised an improved method 

 of separating the arsenic from the organic matter, based upon 

 those of Orfila and Filhol, and a modification of the method of 

 Marsh, by which the arsenic is obtained in a weigliable form. 

 The former is as follows:— 100 grams of the finely divided ani- 

 mal matter is placed in a porcelain capsule with 30 grams pure 

 nitric acid, and moderately heated. At first the mass liquefies, 

 then it thickens and becomes orange-colored. The capsule is 

 taken from the fire and 5 grams pure sulphuric acid are added. 

 Heat is again applied till white fumes appear. Then 10 or 12 

 grams of nitric acid is allowed to flow drop by drop on the resi- 

 due, and it is heated to carbonization. An easily pulverizable 

 mass is thus obtained, which is exhausted with boilini; water, 

 filtered, the filtrate reduced with a few drops of hydro-sodium 

 sulphite, and precipitated as usual, by a current of hydrogen sul- 

 phide. The arsenous sulphide, transformed into arsenic oxide l>y 

 nitric acid, is ready for the Marsh apparatus. This consists of a 

 * See this Journal for December, 1 875, page 474. 



