S D. Hayes on the Distillation of Petroleum Naphthas. 187 
leam, but that they are new substances formed by heat and 
distillation. 
The author says: ‘The uncertainty of the boiling points in- 
dicates that the products obtained at the temperatures named 
above were still mixtures of others, and the question forces itself 
x 
farther on in the report: “The paraffine, with which this portion 
of the oil abounds, does not exist ready-formed in the original 
ployed in the Sarr of distillation, by which the elements are 
° 
the result of an experiment as follows: “Exposed for many 
°, the o1 
ma 
never exceeding 200°, gradually and slowly diminished, grew 
oid and finally left a’small residue of dark brown, lustrous- 
Coking resin, or pitchy substance, which in the cold was hard 
and brittle. e samples of oil employed were very nearly 
colorless. This is remarkable when we remember that the tem- 
perature of the distillation was above 500° F.” : ee 
Tt is remarkable that in this early laboratory investigation 
Prof. Silliman should have noted the production of entirely new 
aye by the destructive distillation of aelaape es such as are 
W only produced in large quantities in manufacturing opera- 
tions. The “cracking” of siblaut as a necessary Pa of 
its distillations in the large way, was not generally recognized 
or admitted for several years after this report was written, and 
“ven now there are many chemists who consider these as a 
Fractional distillations ; but it is only necessary to mix the dis- 
tillates together again and try to reproduce petroleum, to satis- 
s rily prove how different the products are from the original 
bstance, 
The 
_doiling poi it had been float- 
A point above 400° F., probably because 1t een Hoa 
. water exposed to the sia or because it was thick “sur- 
