September 30, 1904.] 



SCIENCE. 



443 



lead were moderately toxic. On the other 

 hand, polished iron, silver, gold, polished tin, 

 aluminum, nickel and a few alloys, as well 

 as celluloid, glass, and hard rubber, had little 

 or no effect. In metals, the smoothness of sur- 

 face seems to have a decided influence. 



BIOCHEMICAL REACTIONS FOR TELLURIUM AND 

 SELENIUM. 



It has long been known that certain micro- 

 organisms are capable not only of living in 

 arsenic solutions, but of reducing arsenic com- 

 pounds to volatile gases containing arsenic. 

 It has indeed been supposed by many that the 

 chief danger to be apprehended from arsenical 

 wall papers is the production of such poison- 

 ous gases by molds. This study has been ap- 

 plied by Professor Gosio, of Rome, to com- 

 pounds of tellurium and selenium, chiefly to 

 tellurites and selenites. The former are much 

 more susceptible to the action of micro-organ- 

 isms than arsenic compounds, showing a de- 

 cided brown or violet coloration with Hypho- 

 mycetes under favorable circumstances within 

 two or three minutes. The tellurites also re- 

 act with the ScMzomycetes and various bac- 

 teria, often giving black precipitates. The 

 compounds formed depend upon the particular 

 kind of microorganism used. The selenites 

 are decomposed almost as rapidly, giving with 

 cultiires of the colon bacillus a red coloration 

 in six minutes. The coloration is probably 

 due to the precipitation of metallic selen- 

 ium. These reactions are suggested for the 

 purpose of detecting certain microorganisms. 



SOURCE OF NORMAL ARSENIC IN THE BODY. 



Now that it is well established that arsenic 

 is a normal constituent of the human body, it 

 becomes of interest to know its source, and 

 this problem has been studied by Gautier, to 

 whom we owe so much of our knowledge re- 

 garding the detection and determination of 

 minute quantities of arsenic. In conjunction 

 with Clausmann he has analyzed a large num- 

 ber of foods, and the following are some of 

 his results. The figures represent the num- 

 ber of micrograms (== 0.001 milligram) in 100 

 grams of substance ; that is, parts per million. 



Fresh beef 0.7-0.8 



Fresh veal 0.5-1 



Milk less than 0.05 



White of egg none 



Yolk of egg 0.5 



Mackerel 2.7-3.9 



Crab, muscle 2.2 



" egg and fat 35.7 



" shell 104 



" whole animal 45.3 



Corn 0.7-0.85 



Wheat bread 0.71 



Cabbage 0.2 



String beans none 



Potatoes 1.12 



Burgundy wine 0.27 



Beer 0.01 



Water of the Seine 0.5 



Sea water, surface 1.1 



" " 10 meters deep 2.5 



White salt 0.7 



English salt 15 



Gray salt 45 



Rock salt 14 



" from Stassfurt , 2.6 



Gautier draws the following conclusions : 

 Muscle contains very little arsenic in compari- 

 son with certain organs, and this can be con- 

 sidered as circulating rather than fixed arsenic ; 

 great variations are found in the flesh of the 

 same species of animal, in fish unquestionably 

 due to the varying arsenic of the sea and to 

 the food; of man's food, certain fish and 

 crustaceans, and gray salt are richest in 

 arsenic, but in general the chief sources are 

 wine, water and salt; some foods contain no 

 trace of arsenic, so that it can not be held that 

 arsenic is universally present, or that it is a 

 constant constituent of the living cell. From 

 Parisian statistics for ten years, it may be 

 considered that a man ingests 20.9 micro- 

 grams of arsenic per day, or 7.66 milligrams 

 per year. In medico-legal cases, it is recom- 

 mended that only such organs as normally eon- 

 tain arsenic merely in traces, be examined, 

 as the liver, spleen, muscle and washed in- 

 testine. If the contents of the intestine show 

 more than one tenth of a milligram of arsenic, 

 we may be sure it did not come from normal 

 food. 



J. L. H. 



