120 PROCEEDINGS OF THE AMERICAN ACADEMY. 



to a paste in a 500 c.c. flask, and noticed formation of mould and crys- 

 tals of metallic arsenic ! Testing this as before, he found arsenic. 



No proof of the formation of an arsenical gas is given by these 

 experiments. The fermentation, which was greater in the first series 

 of experiments, undoubtedly produced enough volatile organic matter 

 to reduce the silver solution in the light. The failure to test the 

 silver solutions for arsenic deprives the results of value, though it is 

 quite possible, in the light of recent work, that a volatile compound 

 was formed. 



Hamberg,* in 1874, tested the air of a room for the presence of a 

 volatile arsenic compound. He used a large dry room which had 

 been papered for 25 to 30 years with a paper of which 1 sq. cm. 

 gave, in the Berzelius-Marsh tube, a thick opaque crust of arsenic 

 6 cm. lono-. Arsenic and arsenious acids were found in the coloring 

 matter. The persons who let the room had not perceived any injury 

 to themselves or to others. 



A series of tubes was hung on the wall opposite the windows, and 

 the air of the room was drawn through them for a month, the door 

 and windows being closed. During the experiment an alliaceous 

 odor was occasionally observed. The first four tubes were U tubes, 

 of which the first was empty and the next three contained cotton wool. 

 Next came two Liebig bulb tubes with a solution of argentic nitrate 

 in each, and between these and the aspirator was an empty guard 

 U tube. 2,160 litres of air were drawn through the system. After 

 a week a black precipitate appeared in the first silver solution, and 

 later in the second. 



The tests were made by the Berzelius-Marsh method. From the 

 first U tube a slight film of arsenic was obtained, in the second (con- 

 taining cotton) likewise a trace, while the third and fourth contained 

 none. The silver solution was filtered and the precipitate found to be 

 silver, with some sulphide of silver. Ammonia gave a faint yellow 

 precipitate in the filtrate. The latter was precipitated with hydro- 

 chloric acid, and the filtrate after evaporation with sulphuric acid intro- 

 duced into the Marsh flask. In ten minutes a brown, film appeared, 

 which increased after an hour to an opaque brown crust. The second 

 silver solution, treated similarly, gave but a faint film. 



Hambere is the first from whose results a definite conclusion can 

 be drawn, and his work is of particular value from having been done 



* Pharmac. Journ. and Transactions, [3], V. 81; also, Nord. Med. Archiv, 

 VI. No. 3. 



