814 CHARLES ROBERT SANGER. 



ever it was necessary to improve the methods of testing for arsenic, 

 so that the quantity of poison could be detected with accuracy, even 

 when it was present in very minute amounts. Owing to its frequent 

 use in criminal cases very delicate tests for arsenic had been already 

 worked out, but these show^ed only its presence or absence, not how 

 much existed in the object tested; for further development therefore 

 Sanger adopted the best of these — the Berzelius-Marsh test — in 

 which the arsenic was detected by a stain (mirror) on a capillary tube ; 

 and his improvement consisted in producing all mirrors under identical 

 conditions, when by comparing that from the object under examina- 

 tion with a set made from known weights of arsenic the quantity 

 could be determined with surprising accuracy. Armed with this 

 delicate quantitative method he studied the amount of arsenic in the 

 excreta of persons living in arsenical surroundings, and found that 

 this depended on the amount of exposure to the wall papers, curtains, 

 carpets, or other sources of the poison. In one case even the quantity 

 of arsenic obtained from one patient was half as great as that obtained 

 from another exposed to the same conditions twice as long each day. 

 Further, when the sources of the poison were removed, the arsenic 

 gradually disappeared from the excreta at the same rate as the morbid 

 symptoms vanished. 



He was now ready to take part in the battle raging between the 

 two camps, into which chemists at that time were divided, one main- 

 taining that the connection between the morbid disturbances and an 

 arsenical environment was proved, the other with equal ^'igor asserting 

 that it was not. The frequent discussions of the question up to this 

 time had consisted of a lively fusillade of assumptions and theories 

 from both sides, which like a sham fight with blank cartridges had little 

 result except noise. Sanger's thoroughly established facts therefore, 

 thrown into this wordy warfare like a volley of shot, swept opposition 

 from the field and converted to his views all, not too prejudiced to be 

 open to conviction. 



This establishment of the connection between these obscure diseases 

 and arsenic was a service of great importance to the world as well as 

 to chemistry, since it gave the physician a means of secure diagnosis 

 and a certain cure for them; and further his results were used in an 

 important study of the general relation between nervous disorders 

 and chronic poisoning with small quantities of various agents. 



It will be of interest next to consider how he had been fitted for this 

 triumph b^^ inheritance and training. His taste for study came 

 directly from a line of scholarly ancestors, graduates of Harvard 



