IX CASES OF POISONING. 273 



still passing, the gas issuing from the orifice of the 

 tube will have a distinct garlic odor if the deposit 

 consist of arsenic, but will be inodorous if antimony 

 only be present. The following reactions may also 

 be applied to distinguish arsenic and antimony. 



The arsenical spots deposited upon porcelain disap- 

 pear when moistened with a concentrated alkaline 

 solution of hypochlorite of soda ; those of antimony, 

 however, are not affected by this reagent. If the spots 

 consist of arsenic and antimony, the latter not exceed- 

 ing 5 per cent., the spots will also be entirely dissolved. 

 Spots or mirrors of arsenic disappear when moistened 

 with a drop of nitric acid, and gently warmed, forming 

 a clear solution. If a drop of nitrate of silver be added 

 to the solution, and a glass rod moistened with caustic 

 ammonia be held over the liquid, but not allowed to 

 touch it, the mixture assumes a yellow color, from the 

 formation of a precipitate of arsenite of silver. Some- 

 times, if too strong an acid or too great a heat have 

 been applied, the precipitate consists of reddish-brown 

 arsenate of silver. This characteristic color is always 

 produced by nitrate of silver, when the arsenic spots 

 are dissolved by placing the capsule over a vessel 

 containing solution of chloride of lime and sulphuric 

 acid. 



It is true that spots and mirrors of 'antimony also 

 disappear when treated with nitric acid, the antimony, 

 however, is not dissolved, but merely converted into 

 white oxide, which gives no reaction with solution of 

 nitrate of silver. The antimony dissolves in a mixture 

 of one drop of nitric acid and one drop of hydrochloric 

 acid ; if the greater excess of acid be carefully evapo- 

 rated, and sulphuretted hydrogen-water be dropped 

 upon the residue, a fiery-red precipitate of sulphide of 

 antimony is produced. If the spot had consisted of 

 arsenic, a lemon-yellow precipitate would have been 

 obtained. 



If the spots be moistened with sulphide of ammonium 



