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CHEMISTRY. — The colorimetric determination of acetylene and its 

 application to the determination of water. E. R. Weaver. Bureau 

 of Standards Scientific Paper No. 267. Pp. 39. 1916. 



A colorimetric method for the detection of small amounts of acety- 

 lene has been developed in the course of an investigation upon the 

 determination of small amounts of water by the use of calcium carbide. 

 The results upon the quantitative determination of water have not 

 been satisfactory, but a simple and very sensitive qualitative test for 

 water is easily made. 



The method for the determination of acetylene has been worked 

 out successfully. The determination is made by conducting the gas 

 to be investigated into an ammoniacal solution of cuprous chloride con- 

 taining gelatine and alcohol, and comparing the red colloidal solution 

 so obtained with a suitable standard, which may be either a solution 

 of red dye or a piece of ruby glass. 



The method is very sensitive. Amounts of acetylene as small as 

 0.03 mg. may be detected and amounts up to 2 mg. may be determined 

 with an accuracy of better than 0.05 mg. 



Hydrogen sulphide and large amounts of oxygen and carbon dioxide 

 interfere with the test, but all of these may be removed by passing the 

 gas to be tested through a hot alkaline solution of pyrogallol without 

 loss of acetylene. 



A qualitative test for water, sensitive to less than 0.1 mg., may be 

 very easily and quickly made by bringing the substance to be tested into 

 contact with calcium carbide in the presence of a solvent for acetylene, 

 which is then decanted or distilled into an ammoniacal solution of 

 cuprous chloride. E. R. W. 



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