SANGER. — VOLATILE COMPOUNDS OF ARSENIC. 133 



the apparatus having been shown to be free from arsenic, and gave no 

 mirror in 40 minutes. 



Experiment 12. — The paper in this room had a surface of about 

 32 sq. m., each containing 30 mgr. arsenious oxide, making a total of 

 about one gram, a rather small amount for the experiment and the 

 size of the room, but the paper was not quantitatively analyzed until 

 afterward. The room was warm, and was kept closed during the trial. 

 No complaint had ever been made by the occupant of symptoms of 

 arsenical poisoning. The apparatus was set up as in Exp. 11, and 

 air was drawn through it rapidly for five days. No reduction of the 

 silver solution was visible. The latter, after treatment in the usual 

 manner, gave no indication of arsenic. 



Experiment 13. — This room was considerably smaller than the 

 other two. The total amount of arsenic in it was about 3.6 grams. 

 No symptoms of arsenical poisoning were ever noticed by the occu- 

 pant, a boy in vigorous health, who occupied the room only at night. 

 The room was closed and kept at 25°. The apparatus was set up 

 as in the previous experiments and 6,720 litres of air were drawn 

 through the system. There was no perceptible darkening of the sil- 

 ver solution, and, on analysis by the same method as in the previous 

 trials, it was found to be free from arsenic. 



Experiment 14.' — The conditions under which this experiment was 

 performed were, as regards warmth and dampness, more favorable to 

 the formation of a volatile arsenical compound than those of the three 

 previous trials. The occupant of the room suffered from symptoms 

 which were clearly due to arsenic* The total amount of arsenic 

 present in paper and curtains was about 3.9 grams. During the ex- 

 periment the room was closed, and the air was at about 30° and damp. 

 The apparatus was similar to that used before, except that between 

 the guard tubes of cotton wool and the silver solution was placed a 

 small quantity of strong sulphuric acid, just as in Exp. 6, as an 

 additional means of absorption. Air was drawn through the system, 

 at intervals for 22 days, the total amount being 1,323 litres. The acid 

 had increased in volume considerably by absorption of moisture, but 

 there was no evidence of reduction as in Exp. 6. The silver solution 

 was slightly darkened and contained a slight black precipitate. Nei- 

 ther sulphuric acid nor silver solution gave any test for arsenic. 



In none of the above trials was any alliaceous odor observed, either 

 from the fermenting material or in the air of the rooms. 



* This case (2) is described in the following article. 



