August 11, 1911] 



SCIENCE 



163 



charcoal with absorption of COj produced, 

 explosion with CO, oxidation of fused 

 mixture of sodium carbonate and CrjOg 

 and determining the amount of NaoCrOi 

 produced, and absorption in absolute alco- 

 hol; and none is satisfactory. There is no 

 good test for N,0 known to me. Dr. 

 Stevenson and the author devised a new 

 method, which gives accurate results in 

 hands skilled in the manipulation of gases. 

 It depends upon passing a definite quan- 

 tity of the gas over heated copper gauze, 

 after a preliminary treatment to remove 

 oxygen, or compounds which produce cop- 

 per oxide, from the sample, and then pass- 

 ing hydrogen through the apparatus, ab- 

 sorbing the water formed. 



The following table, which is self-ex- 

 planatory, exhibits the results of our 

 analyses of compressed nitrous oxide as 

 supplied by American manufacturers: 



Nitrous oxide which is to be used for 

 anesthesia should contain at least 95 per 

 cent, of NjO and no solids, liquids, com- 

 bustible organic matter, chlorine or other 

 oxides of nitrogen. A small amount of 

 carbon dioxide, according to the investi- 

 gations of Gatch, can have no evil effects. 

 If present, however, the per cent, should 

 be known. 



ETHYL ETHER 



Experience of expert anesthetists, not 

 accounted for by idiosyncrasy, obtained 

 in the use of ethyl ethers supplied by 

 various manufacturers in numerous sur- 



gical cases, furnished one of the motives for 

 my investigations into the chemistry of 

 anesthetics. The standards laid down by 

 the various pharmacopcpias of the world 

 are not uniform. In view of that fact 

 alone, a thorough investigation seemed 

 called for. Enquiries addressed to large 

 consumers of the solvent in manufactur- 

 ing processes adduced further need for 

 satisfactory methods of determining the 

 purity of ethyl ether and of detecting im- 

 purities introduced, or proving their ab- 

 sence if eliminated, in the modification of 

 raw products used in its manufacture. 

 The presence of small amounts of sub- 

 stances has oftentimes been the cause of 

 a chemical reaction ijroceeding in a par- 

 ticular direction by virtue of a so-called 

 "catalytic" or other unknown action. So 

 the presence of even traces of certain sub- 

 stances, as peroxidized compounds, alde- 

 hj'de, etc., may have caused some reactions 

 to be incorrectly explained, or to follow 

 an unusual, or unaccounted for, route. 



Ethyl ether is still made commercially 

 by the historical process of treating alcohol 

 with sulphuric acid, hence the misnomer of 

 ".sulphuric ether." Although a number of 

 .synthetic processes have been proposed, 

 some of which have been tried out, none 

 has proved a commercial success.^ 



° In this connection, reference may be made to 

 the method devised by Fritsche for the prepara- 

 tion of ether free from alcohol. In this method, 

 gas containing ethylene is treated with sulphuric 

 acid {Z. anal. Chem., 36, 298; U. S. Patent No. 

 475,640, January 19, 1897), and the ethyl-sul- 

 phuric acid so obtained is converted into ether 

 and sulphuric acid by means of water. This proc- 

 ess was operated on a commercial scale in this 

 country for some time, but it was reported that 

 the industry was destroyed by the Denatured 

 Alcohol Act (Bull. 92, TJ. S. Dept. of Commerce 

 and Labor, Bureau of the Census, 1909, p. 96). 

 It is likely, however, that a similar industry may 

 be revived, as natural gas might serve as a suit- 

 able material from which to prepare ether (cf. 



