THE ELA10METER. 
25 
consistence is to be observed. Messrs. Soubeiran and Blon- 
deau recommend, in estimating tbe consistence of the solidi- 
fied oil, to strike its surface with a glass rod ; and they apply 
the term sonorously firm to oil which becomes sufficiently 
solidified to afford a manifest sound, on percussion ; they 
apply also the terms firm, rather firm, having the consis- 
tence of suet, soft consistence, the consistence of congealed 
oil, to those samples of oil which acquire a consistence 
more or less solid. 
By neither of these methods is it possible to determine 
with certainty the presence of poppy oil in oil of olives, 
unless the sample contain at least one-tenth of the former. 
Of these two processes, that of Poutet is undoubtedly the 
best ; and yet this, according to the above named chemists, 
is, in many respects, deficient. Thus, not only does it fail 
to determine the proportions in which the two oils may be 
mixed, but it offers the great inconvenience of requiring 
the employment of a re-agent immediately after it has been 
prepared, of occupying a considerable length of time, and 
of requiring a certain expertness of manipulation ; for the 
solution of the mercury in nitric acid, resulting from the 
spontaneous action of these two bodies, is not so uniform 
in its composition as to ensure always the same effect. This 
re-agent sometimes fails to produce the expected effect, and 
it is remarkable that when this takes place, the solution 
does not crystallize after standing for a day. Messrs. Sou- 
beiran and Blondeau recommend that no account should be 
taken of the experiments, if the remainder of the solution 
which has not been used is found not to have crystallized ; 
and in all cases to repeat the process so as to guard against 
errors. 
My process is performed in a very much shorter time 
than that of Poutet ; it usually occupies only a quarter of 
an hour. It affords indications of the smallest quantity of 
vol. x. — no. i. 3 
