B1SMUTHI ET AMMON I/E CITE AS. 
545 
sium in the form of small globules more or less adherent to each other. The drying 
of the washed metal must be accomplished as rapidly as possible, at a temperature not 
higher than the boiling-point of water. 
Another mode of producing magnesium has already been referred to. This consists 
in employing the decomposing power of the galvanic current. This mode of reducing 
magnesium was first successfully employed by Bunsen ; but the following instructive 
and simple experiment is due to Matthiessen:—Take a common clay tobacco pipe with a 
bowl nearly globular in shape. In the cavity of the latter fuse some of the double chlo¬ 
ride of magnesium and potassium over a gas flame. When the salt is fused pass up the 
pipe stem a fine iron wire, and allow it to project into the bowl, so as to have its point 
well below the surface of the fused salt. This wire should be connected with the nega¬ 
tive pole of a battery of about six elements, the positive wire of which is terminated 
by a piece of gas coke which is made to just touch the surface of the fused mass. De¬ 
composition at once commences, the result of which is the deposition of minute glo¬ 
bules of metallic magnesium. This is a most interesting experiment, and one very- 
easily performed without the least danger. 
It must be recollected that the chloride of potassium present in the double salt 
plays but a mechanical part, and has not anything directly to do in the reduction of the 
metal. 
III .—Purification of the Metal by Distillation. 
The purification of the metal by distillation is the most certain and effectual method 
which can be adopted, and the invention of the apparatus by means of which this ob¬ 
ject can be accomplished on the large scale in an atmosphere of hydrogen is due to the 
ingenuity of Mr. Sonstadt. We may mention that the manufacture of magnesium on 
the large scale, according to Mr. Sonstadt’s patents, is now being extensively carried on 
by Messrs. Mellor and Co., of Manchester. The last operation which magnesium has 
to undergo before it reaches the hands of the photographer consists in being formed 
into wire. Owing to the low degree of ductility possessed by magnesium this is a 
matter of considerable practical difficulty, as it cannot be easily drawn in the ordinary 
way into wire, but requires to be forced through small apertures in a steel block, the 
metal being kept at a heat below redness, at which point it is much more malleable 
than at ordinary temperatures. On this point, however, we can offer but little precise 
information, as the best mode of magnesium wire making is kept secret. Magnesium, 
when pure, is a silver-white metal, of specific gravity T75. It presents a crystalline 
structure, and is rather brittle. Its equivalent is 12. It exhibits much chemical ana¬ 
logy to zinc, but for certain reasons it is generally classed with the metals of the alka¬ 
line earths. It melts and volatilizes at nearly the same temperature as zinc. It does 
not easily oxidize in dry air, but if moisture be present it is rapidly covered with a film 
of hydrated oxide. It is quickly dissolved by diluted sulphuric acid with formation of 
Epsom salt. When thrown on a little very concentrated hydrochloric acid, it bursts 
into flame for an instant. It is not acted on by a mixture of concentrated nitric and 
sulphuric acids. It burns with great brilliancy when heated in the vapour of iodine and 
sulphur, but less brightly in that of bromine. It also burns in chlorine. 
Professor Roscoe has estimated the expenditure of magnesium at ten grains for each 
portrait taken with the camera ; but, even with the chemicals in good working order, 
this may be considered the minimum weight of metal required to be burnt. In conclu¬ 
sion, we may observe that the steady combustion of thick wires of magnesium may be 
materially facilitated by having the wire flattened out by passing between heavy rollers. 
This “ ribbon ” can be now purchased, and it burns more steadily and can be ignited 
more easily than the round wires at present in use .—British Journal of Photography 
and Medical Press. 
BISMUTHI ET AMMONITE CITRAS. 
BY N. GRAY BARTLETT. 
A preparation, under the somewhat empirical name of “ Liquor Bismuthi (Schacht),” 
was introduced to the profession some years since in England, and more recently it has 
been the subject of several notices in foreign medical publications. 
This liquid contains a bismuthic salt in permanent solution, and is miscible with 
