33 



mentor, M. Signoret, has, according to his assertion, far 

 exceeded this. He states, that he has obtained stains 

 when the arsenic formed only the Wi0 ^ t000 part of the 

 liquid employed. In this case again, supposing the liquid 

 to be pure water, the arsenic present would be nearly in 

 the proportion of 1 grain to 285f gallons of water. It 

 appears to me, however, that this statement requires further 

 confirmation. In some experiments made by Mr. Taylor, 

 it would appear, that he obtained slight brown annular 

 stains with the 1080th part of a grain of arsenic. The 

 amount of dilution in that case was equal to 1>00 o i000 

 with the 720th part of a grain, on the dilution being equal 

 to 800,000, the stains were much more decided — with ,£, 

 grain tbe dilution being equal to 48,000, stains were pro- 

 duced, sufficiently characteristic to be safely relied upon in 

 legal medicine. 



From experiments which I have made, about i'oo 

 of a grain in 5 fluid oz. of liquid, which, considering it as 

 pure water, would give a dilution equal to 218,750, yielded 

 60 distinct stains on porcelain, and 12 indistinct stains. 

 In another experiment, i grain of arsenic was mixed 

 with 2 fluid oz. of chocolate containing cream and sugar, 

 the organic matter was destroyed by nitric acid, and the 

 residue placed in the hydrogen apparatus, with 5 fluid oz. 

 of liquid, being a dilution equal to 21,875, supposing the 

 liquid to be pure water, distinct films were obtained, 85 in 

 number, and about 12 indistinct stains. In all the above 

 experiments, the degree of dilution is calculated upon the 

 supposition that the liquid was pure water, but in truth, 

 water and sulphuric acid were used, and as the latter is much 

 heavier than the former, the relative weight of the arsenic 

 and liquid would be even less than the quantities specified. 



I shall conclude what I have to say on this subject by 

 directing your attention to a test of reduction which has 



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