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Professor Arthur W. Crossley 



[Feb. 5, 



Once more referring to the patent, these words are found : — " It 

 is not necessary to employ pure hydrogen for the purpose of the 

 present invention ; commercial gas mixtures containing hydrogen, 

 such as water gas, may also be used." Again, that may be so, but 

 these gas mixtures will not all be equally efficient, hence we encounter 

 more points which have to be put to the test of experiment. The 

 results of such experiments are sufficiently indicated in Figs. 4 and 5, 

 which show the effects produced by the presence of arsenic and 

 sulphur in the hydrogen, or by using commercial gases, such as 



Fig. 5. 



water gas. By nnpurified hydrogen is meant the gas such as would 

 be obtained from a good specimen of zinc without further removal 

 of impurities. Hydrpgen containing arsenic was generated from an 

 ordinary sample of zinc. Hydrogen containing much sulphur refers 

 to the gas passed through a very dilute solution of sulphuretted 

 hydrogen in water. 



The effect of hydrogenation on a variety of acids and oils, in- 

 dicated by the decrease in their iodine values and by the melting 

 points of the products, is shown by the figures in the following table. 



Many other points still remain, requiring investigation, such as 

 the influence of hydrogen under diminished or increased pressure 

 and tlie refining of the fatty body, but these may be dismissed on the 



