W. SkEY.—On the Mineral Oils of New Zealand. 253 
a rule, the more carbonaceous the oil, the greater its specific gravity and the 
higher its volatilizing point. 3 
Petroleums are, as a rule, mixtures of hydrocarbon oils differing very 
greatly in density and consequently in volatilizing points, charged more or less 
with paraffin—a hydrocarbon oil solid at common temperatures ; and also with 
bituminous or pitch matters, to which last they owe their colour; and it has 
been found that with most or all our petroleums their lightest and their 
heaviest oils are unfit for the highest use we can put them to—that is, for 
illuminating purposes ; ‘consequently they are separated from the rest by 
fractional distillation, and the oils of intermediate density thus obtained only 
require treatment with sulphuric acid and an alkali successively, and to be 
finally re-distilled, to fit them for their destined use, the acid being used to 
clear the impurities contained in the oil, and so to convert them into such a 
form that they can be removed from the oil by water. 
It will be observed how very simple the process of refining these oils is, 
all that is required being steadiness in the distillation, the use of certain 
chemicals in quantities proportionate to the amount and nature of the 
impurities present in the oil operated upon, and the proper division of the 
distillate. I may state that these oils are far easier to perify than those 
obtained by the destructive distillation of any kind of carbonaceous substance. 
Having thus stated briefly the nature of these oils, and the means 
necessary to fit them for illuminating purposes, I will now proceed with 
the subject of this paper, in the hope that, by the aid of the foregoing 
remarks, I may be understood throughout, even by those who may have 
been hitherto unacquainted with the manufacture in question. 
The oils I have had the opportunity of examining up to this time are of 
three distinct kinds, and from as many distinct localities : 
l. The Sugar Loaves, in Taranaki Province. 
2. Poverty Bay, on the east coast of the Province of Auckland. 
3. Manutahi— Waiapu, East Cape. 
l. The first, that from the Sugar Loaves, is a very remarkable oil, its specific 
gravity being no less that -960 to -964 at 60° Fah., water at 1. The heaviest 
petroleum mentioned by Gesner, :927, has a specific gravity of about :930. 
All the various samples which have been submitted have the same physical 
characters, having a dirty green colour by reflected light and being opaque, 
unless examined in thin films, when it has a deep red colour by transmitted 
At 60? Fah. it is quite liquid, and though at lower temperatures it has 
considerable consistency, yet when reduced to 5? Fah. it does not become 
solid. 
It has a mawkish but not unpleasant odour, being very different in this 
