28 PROCEEDINGS OF THE AMERICAN ACADEMY. 



serve as a convenient receptacle for ice or ice vi^ater, by means of 

 which a low temperature may be steadily maintained. This interior 

 vessel also serves a good purpose in economizing time and fuel in 

 heating the bath, as it diminishes the cpnntity of oil required to cover 

 the worm. It is made to extend to within about three inches of tiie 

 bottom of the bath, and large enough to fill a greater part of the 

 space in the centre of the coil." It will therefore be seen that it was 

 uot Warren's intention to use this apparatus in any sense as an air 

 bath. It is to be used solely as a liquid bath. 



Since the principal object was to identify the individual constituents 

 and to determine their approximate quantities, it was only necessary 

 to collect our products within such close limits of temperature com- 

 parable with boiling points already accurately determined that they 

 should yield satisfactory analytical data. In successive distillations, 

 collecting at first within o°, then within 2°, and finally within 1°, 

 after the fifth distillation the fractions collected rapidly, wiih increasing 

 quantities at temperatures near boiling points of well known hydro- 

 carbons C„H2„ + 2) ^"^^ ^t certain other points at which an equilibrium 

 in boiling points seemed to be established by mixtures. It was only 

 with much ditficulty that some of these mixtures could be se[)arated 

 into their constituents. We had occasion to recall the remark of War- 

 ren concerning the greater amount of labor involved in determining 

 the absence of definite compounds in such mixtures than in proving 

 the presence of well defined hydrocarbons. The fractions containing 

 the aromatic hydrocarbons will be considered together. The products 

 collected for vapor density determinations were purified as completely 

 as possible by the removal of unsaturated hydrocarbons, sulphur com- 

 pounds, and the aromatic hydrocarbons. For the removal of sulphur 

 compounds, each fraction was thoroughly agitated with alcoholic mer- 

 curic chloride. After washing with water, there remained in solution 

 not more than 0.02 or 0.03 per cent of sulphur when the mercuric 

 chloride gave a crystalline precipitate, which was the case in distillates 

 below 150°, provided they were collected at first in vacuo. In a former 

 paper * it was stated that alcoholic mercuric chloride removed two thirds 

 of the sulphur. Those experiments were made with refinery distillates, 

 which do not behave the same towards mercuric chloride as vacuum 

 distillates. In higher fractions somewhat more sulphur is retained, 

 and with increasing boiling points even the mercury itself in consider- 

 able quantity may be held in clear solution, either in the form of 



* Amer. Chem. Journ., 1894, p. 88. 



