SANGER. — CHRONIC ARSENICAL POISONING. 177 



In conclusion, it must be remarked that both Gosio's and my work 

 have shown that a very small amount of arsenic may be quite as good 

 a source of the volatile compound as a very large amount. Hence the 

 limit that can be set as a dangerous amount of arsenic in a wall paper 

 is a matter which should be very carefully considered. It has been 

 thought by many that a paper containing under 0.1 gr. per square yard 

 (8 mgr. per sq. m.) was harmless. If the arsenic were given off as 

 dust alone, perhaps this limit would be sufficient, but, with the chance 

 for the formation of the volatile compound, we cannot, I think, say that 

 0.1 gr. per square yard is harmless. The matter of limit emphasizes 

 the need of a quantitative analysis of the paper. By the process I 

 have described and referred to here, this is a simple matter, and every 

 paper should be reported, not in the indefinite " traces," " large 

 amounts," " dangerous quantity," etc., but with the approximate fig- 

 ures, so that the physician may himself decide as to whether the paper 

 should be rejected or not. 



Washington University Chemical Laboratory, 

 Saint Louis, September, 1893. 



vol. xxix. (n. s. xxi.) 12 



