341 



temperature of 154-155° C. ; was inactive to light; had a specific gravity at 

 19° C. = 0-7927; and a refractive index at 19° C. = 1-4437. This gives by the 

 Lorenz-Lorentz formula a molecular refraction very closely approaching that 

 required for the C,„H.,„ molecule. When dissolved in chloroform and a very 

 dilute solution of bromine in chloroform added, this was not discoloured at once, 

 but the bromine slowly acted upon it by substitution, hydrobromic acid being 

 evolved. An analysis gave the following results : — 



0-1251 gram gave 0-1593 gram H,0 and 0-3934 gram CO.^. 

 C. = 85-77 P^'^ cent, and H. = 14-15 per cent. 

 Cj„H,„ requires C. = 85-71; H. = 14-29 per cent. 



This hydrocarbon is thus shown to belong to the Cj„H.,„ or menthane series. 

 Its inactivity to light, its saturated nature, its stable character, the results of its 

 physical properties and analysis, all go to show that this is so. The known men- 

 thenes too, all have a higher specific gravity. The activit}^ and unsaturated 

 nature of the product of the first distillation, however, indicate that menthene 

 or menthenes were present originally in the latex, but that it, or they, had under- 

 gone alteration during the time which had elapsed since the oil was first separated, 

 and their original character had been greatly changed. From the results of the 

 distillation there was originally in the oil about 20 per cent, of misaturated hydro- 

 carbons belonging, probably, to the menthene group, but which had evidently 

 undergone considerable alteration. 



Free Acids. 



The aqueous distillate from the 420 grams of the latex was filtered through 

 wet paper; it measured 750 c.c. ; 100 c.c. required 12-5 cc^^NaOH to neutralise, 

 so that the 750 c.c. contained 0-562 gram volatile acid considered as acetic, or 

 0-134 psr cent. The remainder was neutralised with barium hydrate, evaporated 

 to dryness and heated at 100-105° C. to constant weight. 0-3228 gram of the 

 barium salt gave 0-2738 gram barium sulphate = 84-82 per cent. 



Both butyric and acetic acids were shown to be present in the distillate, 

 so that if these acids were alone present, they were in the following proportions : — 

 Barium acetate = 60-38 per cent.. Barium butyrate = 39-62 per cent. 



The Gum. 



The air-dried gum boiled out from the 680 grams of the latex, and precipi- 

 tated by alcohol, weighed 50 grams = 7-35 per cent. A small amount was 

 extracted later from the residue after the resin had been removed, thus bringing 



the total gum in the latex to 8 per cent. 



