12 ARSENIC IN PAPERS AND FABRICS. 



arsenious acids, alkaline arsenates, and arseiiites, chlorids, and sulphids of arsenic, 

 and even arsenic itself) . 



The reaction of these molds on compounds of arsenic is extremely delicate; it 

 is sensitive to infinitesimal traces. For amounts of any importance, provided 

 that they are not so large as to be toxic to the molds, the phenomenon lasts for 

 months and can be perceived even at a distance. After breathing the gas with this 

 odor of garlic for a long time one feels ill, as I have had occasion to discover in 

 experimenting on myself. 



It would appear that this paper settled beyond a doubt the possi- 

 bility of the formation of gaseous arsenical compounds from wall 

 papers containing this element, yet because of the many conflicting 

 results which had been obtained in times past even this most con- 

 vincing paper could not be accepted without substantiation. To 

 Sanger a is due the credit of substantiating Gosio's results and defi- 

 nitely settling this vexed question. He obtained from Gosio cultures 

 of Penicillium brevicaule upon strips of potato containing different 

 amounts of arsenic. In one of Sanger's experiments 1 gram of arseni- 

 ous oxid was mixed with flour and water in a liter flask and the mix- 

 ture inoculated from the tube marked "patata essente di arsenico" 

 (potato impregnated with arsenic). Air was first passed through a 

 silver nitrate solution, next through the flask, and then through a 

 system of which two absorption bulbs containing silver nitrate solution 

 were the essential part. After two weeks' passage of air through the 

 flask the growth of mold was abundant, but on opening it there was 

 no odor of garlic and the silver nitrate solutions gave no test for 

 arsenic. This was doubtless due to the fact that the P. brevicaule 

 could not endure the large amount of arsenic present and died out 

 while other more resistant but nonarseno molds flourished. That 

 this assumption was true was shown by an examination of the molds 

 present, no P. 'brevicaule being found. 



In another of Sanger's experiments three Erlenmeyer flasks were 

 fitted with double-hole rubber stoppers, through which passed two 

 tubes, one reaching just below the stopper and one to the bottom of 

 the flask. Potato pulp was added to each flask and moistened with 

 a solution of sodium arsenate, so that each flask contained about 0.1 

 gram of arsenic oxid. They were thoroughly sterilized and inocu- 

 lated from the Gosio tube marked "patata bagnata in una soluzione 

 di As 2 O 5 " (potato bathed in a solution of arsenic oxid). The flasks 

 were joined in a system, and, as in the previous experiment, both the 

 incoming and outgoing air was passed through a silver nitrate solu- 

 tion. At the end of twelve days, when the flasks were disconnected, 

 an alliaceous odor could be observed, and the silver nitrate solution 

 through which the air of the flasks had passed showed a well-defined 

 mirror of arsenic amounting to about 0.01 milligram when tested in 

 the Marsh apparatus. In this and other experiments all the reagents 

 used were carefully tested and found to be free from arsenic. The 



" Proc. Amer. Acad. of Sci., 1894. 



