816 CHARLES ROBERT SANGER. 



His work for the Ph. D. consisted of an investigation of substituted 

 pyromucic acids, but the research on arsenic, ah-eady described, soon 

 removed him from this field of pure organic chemistry cultivated so 

 successfully by his master. Continuing study in his chosen line, 

 after he had proved the reality of arsenical poisoning from wall papers, 

 he attacked a puzzling mystery, which had baffled all attempts to 

 penetrate it, but with this he proved less fortunate. The s^Tiiptoms 

 of wall paper poison are divided into two classes, one consisting of 

 irritations of the mucous membrane obviously produced by arsenical 

 dust, the other appearing in far reaching disturbances of the nervous 

 system. Disorders of this latter class have been observed, when 

 poisonous dust was nearly excluded, since the arsenic was contained 

 in a glazed paper, or even, when its formation was impossible, because 

 the arsenical paper was covered by one or more free from arsenic, so 

 that in these cases the poisoning could have been due only to a gas; 

 but here was the mystery — all attempts to detect an arsenical gas had 

 failed (with two exceptions) whether in rooms with poisonous wall 

 papers, or in mixtures of arsenic with organic matter, which should be 

 even more efficient. During the earlier theoretical stage of the dis- 

 cussion those contending against the arsenical source of the nervous 

 disorders were fond of arguing, that if arsenical they could be due to a 

 gas only, as this gas could not be detected, it did not exist, and there- 

 fore the symptoms were not caused by arsenic. I think this is a fair 

 statement of this argument, which in spite of its want of logic carried 

 much weight, until Sanger destroyed it, by his discovery of arsenic 

 in the excreta. But, although he proved in this way the existence of 

 an arsenical gas, the puzzle still remained, as to what the gas was, 

 how it was formed, and why it escaped detection. To the study of this 

 problem he devoted a great deal of time, but, as he followed the 

 methods of his predecessors, he was no more successful than they, 

 and in spite of the most careful work did not succeed in detecting 

 a trace of an arsenical gas. The truth was a new line of attack was 

 needed, and this came from cryptogamic botany instead of chemistry, 

 when Gosio announced his discovery that an evil-smelling gas con- 

 taining arsenic was given off by three sorts of moulds growing in 

 contact with arsenic and organic matter. Sanger at once repeated 

 Gosio's experiments with the only one of these moulds accessible to 

 him (mucor muccdo), but without success. Later however with a 

 specimen of the most efficient sort {penicillium brevicaule) sent him 

 by Gosio he succeeded in confirming the Italian's results. This 

 important confirmation of the efficiency of moulds in the production 



