68 SIXTH REPORT — 1836. 



But what she stated proves satisfactorily that her evidence was correct, for 

 she said that " the gruel was of a nasty red colour," when nothing had 

 transpired of red arsenic ; and had she invented a tale to account for the 

 appearance of the body, or had she spoken from what she heard from 

 others, she would have said the gruel was of a yellow colour. 



From what occurred, therefore, it is clear that the realgar of the 

 shops would cause death ; that half an ounce given at twice (by the 

 prisoner's confession) was sufficient for that purpose ; that realgar 

 became orpiment during putrefaction ; that realgar, like arsenious 

 acid, had a tendency to control putrefaction, and convert bodies 

 into adipocire. 



During the experiments upon this case It was found that the mi- 

 croscopic system of testing, which was first introduced by Dr. Wol- 

 laston, and which Mr. Herapath constantly followed, could be made 

 to improve the very beautiful reducing process proposed by Dr. Chris- 

 tison, and also furnished an excellent method of proving to the jury the 

 presence of arsenic. The whole organic matter having been decompo- 

 sed in boiling nitromurlatlc acid, potash added in excess to prevent the 

 injurious effects of mineral acids on sulphuretted hydrogen, a slight 

 excess of acetic acid poured in, and the sulphuret of arsenic precipi- 

 tated and reduced in Berzelius's tube to the metallic state, and then 

 oxidized, as recommended by Christison, the author found in the subse- 

 quent experiments a modification of Dr. WoUaston's practice very be- 

 neficial. 



Instead of putting the few drops of solution of arsenious acid thus 

 obtained into test-tubes to apply the reagents, he used a china tablet, 

 and having applied a drop of the solution, then a little ammoniacal sul- 

 phate of copper, the green of Scheele became evident by the contrast of 

 colour with the white plate ; but even that might be improved by gui- 

 ding the coloured drop by means of a glass rod down upon a piece of 

 white blotting paper, previously placed on a flat chalk-stone, which by 

 absorbing the solution removed any excess of the blue reagent, (which 

 which was always liable to overpower the colour of Scheele's green,) 

 while it left the latter on the paper, and when dried it could be Intro- 

 duced into a sealed tube, which could be marked by a diamond, in the 

 handwriting of the experimenter ready for Identification before the jury. 

 Mr. Herapath is satisfied that yo^Tnjth of a grain of arsenious acid might 

 be detected by these means. The other two reagents, ammoniacal ni- 

 trate of silver and sulphuretted hydrogen, can be applied in the same way, 

 and when dried the product may be similarly inclosed. In all cases 

 where a highly oxygenating process is followed, for instance, when the 

 mixture Is boiled in nitro-muriatic acid, or where deflagration with nitre 

 is practised, the arsenical compound Is converted Into arsenic acid, and 

 in passing sulphuretted hydrogen (after the usual precautions) the first 

 portion of the gas is decomposed by giving hydrogen to the oxygen of 

 the arsenic acid, consequently sulphur falls mixed with sulphuret of 

 arsenic, but so extremely light that it takes some hours to deposit ; 

 after which the mixed mass may be collected together, and upon re- 

 ducing it to metallic arsenic the sulphur would be separated ; for from 



