2 PROCEEDINGS OF THE AMERICAN ACADEMY 



found to be necessary in order to secure the precipitation of pure an- 

 timoiiious sulphide : — 



" The precautions here descrihed may seem unnecessary to those 

 who are not familiar with the fact that a solution of antimony in hy- 

 drochloric acid oxidizes with very great rapidity in the air, — fully as 

 rapidly as the solution of a ferrous salt. A solution reduced as we 

 have described, which has at first no action on the iodized starch paste, 

 will strike the blue color after it has been exposed to the air for only 

 a few minutes. This property of an acid solution of antimonious 

 chloride is mentioned by Dexter, in the paper already referred to, but 

 we were wholly surprised by the energy of the action. By means of 

 it, antimony can be dissolved in hydrochloric acid without the aid of 

 nitric acid, or of any other oxidizing agent save the air. if only a cer- 

 tain amount of antimonious chloride has once been formed. "When, 

 after exposure to the air, the solution is boiled over pulverized anti- 

 mony, the solution is reduced, and a further portion of the metal 

 enters into solution. After a second exposure, the same process can 

 be repeated, and so on indefinitely. The process is very slow and 

 tedious, but, in one experiment, we succeeded in bringing into solution 

 in this way several grammes of antimony." 



On the sole basis of this language we have been represented as 

 asserting that such antimony solutions oxidize in the air as rapidly as 

 a solution of ferrous chloride^ and experiments on comparatively dilute 

 solutions of antimonious oxide in hydrochloric acid have been adduced 

 as proofs that our observation was incorrect. 



As is evident from the context, the statement just quoted, although 

 the result of a very extended experience, was not based on quantita- 

 tive measurements. What we noticed was that the solutions were 

 very quicldy acted on by the oxygen of the atmosphere, and we freely 

 admit that the expression here italicized is a more accurate description 

 of our observation than the words originally used as quoted above. 

 But our meaning was not left in doubt, for we expressly say, immedi- 

 ately after, that the process is very slow and tedious. In regard to 

 the phenomenon in question, the effects are so obvious, when once 

 attention is called to them, that it is entirely unnecessai-y to confirm 

 our previous observations except so far as to add the following quan- 

 titative determinations, which will serve to give an accurate idea of 

 the extent of the action under the only conditions we have investi- 

 gated, or in regard to which we have written. 



In order to determine the amount of oxidation caused by the action 

 of the atmosphere on a solution of antimony in hydi-ochloric acid, we 



