Peckham and Linton — Trinidad Pitch. 199 



estimated as asphaltene. The distinction made by the use of 

 these two solvents will be noted farther on. The dried residue 

 from the chloroform exhaustion was then put into a platinum 

 crucible and the organic matter burned off. The residue was 

 inorganic or mineral matter, sand, and the small percentage of 

 soluble and non-volatile salts present. The pitch was thus 

 divided into that portion soluble only in petroleum ether, or 

 " petrolene," that portion soluble only in boiling spirits of tur- 

 pentine, and chloroform which together form " asphaltene," 

 and with the petrolene constitutes the " total bitumen " ; also 

 the " organic matter not bitumen " and the " inorganic matter." 



Table No. 1 represents the results of the analysis of the 27 

 specimens described above. Any attempt to classify them as 

 to the locality from which they were obtained by means of 

 these analyses will inevitably fail. Our analyses prove that an 

 average of specimens will show an increase in the proportion 

 of " mineral matter " and of " organic matter not bitumen," 

 as the point from which the specimen is taken is removed from 

 the center of the lake ; yet, the exceptions to this rule are so 

 numerous and marked, that no certainty can attach to the use 

 of these criteria. 



Great value is attached by some experts on asphaltum to 

 the determination of the specific gravity and temperature at 

 which the different specimens soften and flow. These tests 

 might have some value if applied to a pure bitumen which had 

 been proved to change in specific gravity, etc., as it underwent 

 chemical and other changes ; but no such investigation and 

 proof in relation to any asphaltum has been attempted. Such 

 a relation has been assumed but not proved. The fact that 

 Trinidad pitch is a mixture so indefinite that it is almost, if not 

 quite impossible, to select two pieces that have the same pro- 

 portions (as is proved by Nos. 6, 7 and 8) is a sufficient reason 

 why no such distinctions can be based upon such determinations. 

 The average proportions of mineral matter to bitumen in the 

 5 samples of commercial lake pitch taken from near the center 

 of the lake is 100 : 151. No two of them are exactly alike, 

 and the extremes are, lowest 100 : 148, highest 100 : 155. The 

 seven specimens from outside the tramway show greater uni- 

 formity, yet no two are alike and all are below the lowest of 

 the five mentioned above. The average ratio of the land pitch 

 is still a little lower, while the extremes of variation are 134 

 and 146. It is manifest that between these extremes of pro- 

 portion of 100 : 134 and 100 : 155 a marked variation in specific 

 gravity and flowing test must occur, as the sand is about twice 

 as heavy as the bitumen. These extremes of variation include 

 one-sixth of the average amount of bitumen present. 



