Medico-legal contributions on arsenic : containing reports of a number of cases of arsenical poisoning, together with an account of the methods employed in their chemical examination / by Charles H. Porter.

  • Porter, Charles H. (Charles Hogeboom), 1834-1903.
Date:
1862
Catalogue details

Licence: Public Domain Mark

Credit: Medico-legal contributions on arsenic : containing reports of a number of cases of arsenical poisoning, together with an account of the methods employed in their chemical examination / by Charles H. Porter. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

    11/64
    into it. If any arsenic is present, it will be precipitated in the form of tersulphid of arsenic. This is to be collected on a small filter (previously dried at 212 deg. F. and weighed,) then thoroughly washed, and dried at the same temperature as before and again weighed. The increase in the weight of the filter represents the amount of tersulphid of arsenic present. Or the precipitate may be collected on a small filter thoroughly washed, then dilute ammonia added drop by drop, until it is all dissolved; the filtrate and the washings are to be collected in a weighed dish and evaporated to dryness and weighed as above. Each part of tersulphid of arsenic is equal to 0.8049 of arsenious acid, or to 0.6098 of metallic arsenic. Thus supposing the weight of the sulphid of arsenic was 0.345 grains, this is equal to (0.345X0.8049=) 0.277 grains arse- nious acid or to (0.305X6098) 0.210 grains metallic arsenic. 2. Conversion of the sulphid of arsenic into compounds suitable for testing. It is now desirable to make the most characteristic tests for arsenic, some of them are popularly known, and it is expected by courts of justice that they shall- be made when arsenic is found in the examination of a case of suspected poisoning, there are others less known, but at least equally distinctive. Now, al- though it is not necessary to make them all to satisfy a chemist of the presence of arsenic, yet, as in the majority of cases, there is a sufficient quantity present to make all those tests, which are deemed satisfactory by medical jurists, and as it consumes but little time, is it not as well to make all, or at least the greater part of them? Any common test omitted is often seized by the defendant's counsel, and is made to appear as the most character- istic, if not the only reliable test; why not avoid even this slight perplexity, besides otherwise the jury may be misled ; again an accumulation of tests perfectly corresponding with, and corrobo- rating each other, is more satisfactory to them. In fact, the production of a metallic mirror, easily volatilized and readily oxydizable, and which furnishes by oxydation octa- hedral crystals soluble in water, is sufficient evidence of arsenic. Various plans may be adopted to bring the sulphid of arsenic, obtained in the manner just mentioned, into a state fit for making the various tests. The following method is convenient and simple. A part, or the