Chemistry and Physics. 475 



SCIENTIFIC INTELLIGENCE. 

 I. Chemistry and Physics. 



1. The Production of Chloropicrin from Organic Compounds. 

 R. L. Datta and N. R. Chatterjee have found that aqua regia 

 acting upon a great many organic compounds produces chloro- 

 picrin, CC] 3 NO a , which is sometimes called nitrochloroform, or in 

 modern nomenclature trichlorintromethane, a heavy liquid of 

 very pungent odor. Aqua regia decomposes acetone, (CII 3 ) 3 CO, 

 almost quantitatively into chloropicrin, so that the reaction may 

 be employed as the best method of preparing the substance. A 

 mixture of two parts of nitric and three parts of hydrochloric 

 acid is prepared and to this about one-tenth of acetone is gradually 

 added with slight warming, finally on the water bath. The 

 resulting liquid is next subjected to steam distillation and the 

 compound is separated, dried by means of calcium chloride and 

 finally distilled at a slightly reduced pressure. Treated with 

 aqua regia in a similar manner allyl alcohol gave the same pro- 

 duct, ether gave only a little of it, ethyl alcohol was partially 

 converted into it, methyl alcohol gave apparently a slight trace 

 of it, while formic and acetic acids were not decomposed by aqua 

 regia and consequently gave no chloropicrin. Many other organic 

 compounds gave this substance as a final decomposition product, 

 so that the action appears to be very general. — Jour. Amer. 

 Chem. Soc, xxxvii, 567. h. l. w. 



2. The Determination of Gasolene Vapor in Air. — G-. A. 

 Burrell and A. W. Robertson have used two methods for this 

 purpose, one of which is particularly interesting on account of 

 the principle involved. The apparatus consists of a tubular glass 

 bulb with a constriction dividing it into two nearly equal parts. 

 The upper part is charged with glass-wool and phosphorous 

 pentoxide in order that the water vapor in the sample of air may 

 be absorbed, for otherwise it would count as gasoline vapor. The 

 bulb has an upright stem to the side of which is attached by 

 fusion a simple U-shaped mercurial manometer. Above this is a 

 3-way stop-cock with a connection with a vacuum pump and 

 another for admitting the sample. To make a determination the 

 air is pumped out of the apparatus, the sample to be analyzed is 

 let in at atmospheric pressure, the bulb is then placed in liquid 

 air which condenses the gasoline complete^, the air is next 

 pumped out, the stop-cock is closed and the bulb is warmed to the 

 original temperature, and its pressure is read off on the mano- 

 meter. The ratio of this pressure to the pressure of the atmos- 

 phere gives the percentage of gasoline vapor originally in the 

 sample of air. It is unnecessary to know the volume of the bulb. 

 The other method employed for the purpose consisted in burning 

 the gasoline vapor with air or oxygen in a gas analysis apparatus 

 and determining the contraction as well as the carbon dioxide 



