86 REPORT— 1840. 
of numerous cases of poisoning by opium, which had appeared before 
the Middlesex coroners, he had come to the conclusion that the resin 
of opium test for nitric acid afforded only an auxiliary method of 
arriving at the truth, as its characters were frequently verified by 
other organic substances. 
On Bleaching Vegetable Wax. By Mr. E. Soxty. 
In the course of the summer the author made a series of experiments 
on the best method of bleaching vegetable wax, the green colour of 
which is very difficult of destruction, and of course a considerable ob- 
jection to its use in the manufacture of candles. On trying most of 
the methods usually described as being fitted for the purpose, he found 
them all more or less objectionable, or inapplicable on a large scale. 
Some were tedious, requiring a long time for their completion, others 
expensive, whilst others again were inconvenient, from the difficulty with 
which the residuum of the materials employed in bleaching were sepa- 
rable from the bleached wax. The author found that the best effect was 
produced by chlorine; but in this case it was necessary that the mate- 
rials used to evolve the gas should be intimately mixed with wax, and 
then of course the difficulty of separating the residue occurred, and when 
a stream of chlorine was slowly passed through the wax, the process was 
very slow and tedious. He subsequently found that strong nitric acid 
was a very powerful decolorising agent, and it possessed the advantage 
of leaving no residue which was at all difficult of separation ; the expense 
of this process was, however, a great objection to its use. The following 
method was ultimately employed. The wax was melted, a small quan- 
tity of sulphuric acid was poured in, composed of one part of oil of 
vitriol to two of water, and then a few crystals of nitrate of soda were 
stirred in; the whole was then agitated with a wooden stirrer, and kept 
heated. Nitric acid was thus evolved in considerable quantity and 
purity from a large surface, and in such a manner that all the acid 
evolved must necessarily pass through the melted wax. This method 
answered the purpose very completely; the process was cheap and 
rapid, and the residuum being merely a little solution of sulphate of 
soda was very easily removed. When it is desired to employ chlorine 
in place of nitric acid as the bleaching agent, the same process may be 
adopted. 
On a peculiar Class of Voltaic Phenomena. By Mr. SturGEon. 
The author directed attention to some experiments published by 
himself in 1830, and to his theory respecting the electro-chemical 
action of the simplest metals on acid and other solutions. He stated 
that the fact of iron not precipitating copper from its sulphate and 
other solutions, as recently observed by Professor Schénbein, was one 
of the many beautiful phenomena discovered by Keir, and published in 
the Philosophical Transactions for 1790. 
ies St Se 
