Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1922 edition. Excerpt: ...two results do not agree, evaporate the filtrate containing the bituminous matter soluble in carbon disulphide, burn, ignite and weigh the residue. The weight of the ash derived from the bituminous matter soluble in carbon disulphide should be added to the original residue of insoluble mineral matter. This may represent collodial mineral particles, which are not retained by the filter, or else mineral constituents combined chemically with the bituminous matter. Carbenes The expression "carbenes" has been generally applied to that portion of bituminous substances soluble in carbon disulphide but insoluble in carbon tetrachloride. This term was originally proposed by Clifford Richardson.2 This test is of value in identifying bituminous substances, gauging their uniformity of supply, for purposes of factory control, and as a criterion of their quality. Certain hard native asphalts and asphaltites, particularly grahamite, normally contain a percentage of carbenes, whereas petroleum asphalts do not show carbenes unless they are overheated, or over-blown. If more than 0.5 per cent is present in petroleum asphalts, their quality is to be regarded as questionable. Carbenes are found in tars and pitches in varying amounts.3 This test is carried out by following the same procedure as in determining the solubility in carbon disulphide, but replacing the latter with carbon tetrachloride. The carbon tetrachloride must be free from carbon disulphide, which may be insured by distilling it under a dephlegmator, discarding any distillate below 76 C. The solvent is then filtered through calcium chloride, and any free hydrochloric acid removed by blowing dry air through it. 1 "Analysis of Calcareous Asphaltum and Paving Mixtures," by...
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