Separation of arsenic : From the Transactions of the Society of Arts. Vol. LI. The large gold medal was presented to Mr. James Marsh, of the Royal Arsenal, Woolwich, for his method of separating small quantities of arsenic from substances with which it may have been mixed. / [By James Marsh].

  • Marsh, James.
Date:
1842
Catalogue details

Licence: Public Domain Mark

Credit: Separation of arsenic : From the Transactions of the Society of Arts. Vol. LI. The large gold medal was presented to Mr. James Marsh, of the Royal Arsenal, Woolwich, for his method of separating small quantities of arsenic from substances with which it may have been mixed. / [By James Marsh]. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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    large a quantity of mixture as from two to four pints (imperial measure), I then have employed the instrument (tig. 3), which is, indeed, but a slight modification of one of the instantaneous light apparatuses, now so well known and used for obtaining tire by the aid of a stream of hydrogen gas thrown on spongy platinum. It will, there- fore, be of importance only for me to describe the alter- ation which I make when I employ it for the purpose of detecting arsenic. In the first place, I must observe, that the outer vessel a, which I use, holds full four pints, and that the jet of the stopcock is vertical, and its orifice is twice or three times larger than in the in- strument as generally made for sale, and also that there is a thread or wire attached to the cork of the stopcock Z>, for suspending a piece of zinc c, within the bell-glass With an instrument of this description, I have ope- rated on one grain of arsenic in twenty-eight thousand