The coal-tar colors : with especial reference to their injurious qualities and the restriction of their use / a sanitary and medico-legal investigation, by Theodore Weyl, with a preface by Professor Sell, tr. with permission of the author by Henry Leffman.

  • Theodor Weyl
Date:
1892
Catalogue details

Licence: Public Domain Mark

Credit: The coal-tar colors : with especial reference to their injurious qualities and the restriction of their use / a sanitary and medico-legal investigation, by Theodore Weyl, with a preface by Professor Sell, tr. with permission of the author by Henry Leffman. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    of three parts of water and one part of hydrochloric acid, and different drops of the solution tested for tin, by mercuric chlor- ide, gold chloride and hydrogen sulphide, the latter test being tried both before and after the addition of bromine or chlorine water. A black residue, insoluble in the acid, remaining after the treatment of the contents of the boat with hydrochloric acid, may be antimony. //. Liquids, Fruii Jellies, and Similar Substances.—In such cases, a quantity of the material is to be weighed out that shall be equivalent to 20 grams of the dried substance. For raspberry syrup, 30 grams must be taken ; for currant jelly 35 grams, and for red wine, vinegar and such fluids, from 800 to 1000 grams must be used. Smaller quantities may be used only when the full amount is not obtainable. Fruit juices, jellies and such substances are treated exactly as directed above, with hydrochloric acid, potassium chlorate, etc.; dilute, non-acid liquids are concentrated by evaporation, to a small volume, and treated as before; acid liquids are distilled to a small volume, the distillate is mixed with hydrochloric acid and saturated with hydrogen sulphide, any precipitate so ob- tained being added to that obtained from the liquid in the retort similarly treated. B. Procedure for the detection of arsenicum in yarn and fab- rics (§ 7 of the law).* * It is allowable for the investigator to make a preliminary test by Marsh's method, using a sufficiently large quantity of the material, and thus determine the presence or absence of arsenicum. Should the result be negative further procedure is unnecessary. [In this and similar cases, Reinsch's test, which is much more convenient than Marsh's, will be found sufficient for preliminary examination. It is advisable to use a rather large amount of hydrochloric acid, otherwise arsenates may be overlooked. The processes given in the text for the destruction of the organic matter are now not much employed, since the methods involving the use of sulphuric acid with or without nitric, are more rapid and satisfactory. These methods will be found described in Fresenius' Quantitative Analysis and other works of similar scope. Translator.]