14 
THE PHARMACEUTICAL JOURNAL. 
[July 2, 1870. 
the yeast so produced having very little fermentative 
power. 
Cold water extracts of flour and of malt, added to solu¬ 
tion of cane sugar, with which was a little glucose, 
became mucilaginous, and the production of yeast-cells 
in this mucilage may he easily watched. 
The blue mould which forms on infusion of malt, and 
the mould from lemon-juice, were found to act as good 
ferments in solution of grape sugar. 
From some comparative experiments made with grape 
juice, to which various quantities of glucose had been 
added, the author concluded that the fermentation of 
must would be rendered more complete and exhaustive 
by the addition of a certain quantity of glucose. 
The President, in remarking on this paper, said that, 
although it was usual to speak of the yeast plant in con¬ 
nection with fermentation, the organism appeared in all 
its functions to be animal rather than vegetable. The 
products of its secretion, he said, are less complex than 
those it takes in. Moreover, it does not, like plants, 
require light for its vital process; nor does it absorb 
heat, but, on the contrary, gives it off. 
Another paper read at the same meeting was “ On 
Organic Matter in Water,” by Dr. Heisch. 
The author, having been consulted by a manufacturer 
of lemonade, who suddenly found that all his lemonade 
after a few days became turbid, and acquired a disagree¬ 
able odour, found, on examining the liquid under the 
microscope, that it was full of small spherical cells, with, 
in most cases, a bright nucleus. 
Further investigation of the subject led to the conclu¬ 
sion that the source of the evil was organic contamina¬ 
tion of the water used in the manufacture. On putting 
a few grains of the purest crystallized sugar into some 
of the water, it became turbid in a few hours, and was 
found to contain the cells previously described. It 
seemed probable, from inquiries made, that sewage had 
gained access to the well, and to this Dr. Heisch was 
disposed to ascribe the result. Experiments were made 
with various samples of water, to which sugar was 
added, as already described; and in every case in which 
the water used had produced diarrhoea, or other mischief 
of that sort, when employed as a beverage, on treating 
it with sugar, the characteristic cells were developed, 
usually within twenty-four hours, the temperature being 
kept at 60° or 70° F., and light freely admitted to the 
liquid. A minute quantity of sewage itself was added 
to a solution of sugar, which had been previously ascer¬ 
tained to be free from the cells, and the solution was 
soon afterwards found to contain them. 
A number of experiments were made with the view of 
ascertaining whether other substances besides sewage 
were capable of producing organisms such as had been 
observed in the cases referred to, when added to solution 
of sugar; but, although in a few instances growths were 
produced, they never resembled the cells caused by 
sewage. 
The author states that filtering the water through 
the finest Swedish paper does not remove the germs, 
and boiling for half an hour does not destroy their 
vitality. Filtration through a good bed of animal char¬ 
coal was found to be the most effectual mode of removing 
them, and even in this case the charcoal must be freely 
exposed to the air from time to time, or it soon loses its 
purifying power. 
CHEMICAL NOTES TO THE PHARMACOPOEIA. 
BY WILLIAM A. TILDEN, B SC. LOND. 
DEMONSTRATOR OF PRACTICAL CHEMISTRY TO THE 
PHARMACEUTICAL SOCIETY. 
Acidum Arseniosum. Arsenious Acid. —White, ar¬ 
senic of commerce is procured by heating certain 
ores in a current of air. These ores are compounds 
of arsenicum and sulphur, with the metal copper 
or iron, or sometimes nickel and cobalt. Atmo¬ 
spheric oxygen, combining with the sulphur, gives 
rise to sulphurous acid gas, S0 2 ; with the metal it 
forms an oxide ; with the arsenic, As 2 0 3 . This last 
collects in the flues of the furnaces, whence it is re¬ 
moved and purified by resublimation. 
[§ Occurs as a heavy white powder, or in sublimed 
masses, which usually present a stratified appear¬ 
ance, caused by the existence of separate layers, dif¬ 
fering from each other in degrees of opacity. When 
slowly sublimed in a glass-tube, it forms minute 
brilliant and transparent octahedral crystals.] 
White arsenic belongs strictly to the class of bodies 
already described as anhydrides; it is not itself an 
acid, for it contains no hydrogen, but it is supposed 
to form the acid when boiled with water, in which it 
dissolves only sparingly. The formula of the acid, 
although it cannot be isolated, is inferred to be 
H 3 As 0 3 , 
As 2 0 3 +8H a 0=2H 3 As 0 3 
from the composition of its salts ; arsenite of silver 
being Ag' 3 As 0 3 . The potassium arsenite is probably 
formed in preparing Fowler’s solution (liquor ar- 
senicalis) by boiling white arsenic, water, and car¬ 
bonate of potash together. 
When white arsenic is mixed with charcoal, and 
heated in a flask or tube, it loses its oxygen, which 
combines with carbon, and escapes in the form of 
carbonic oxide, and a crystalline sublimate of the 
element arsenicum is formed in the cool part. 
2As 2 0 3 -f“ 3 Co=A? 4 +CCO. 
Arsenious anhydride and soluble arsenites may be 
recognised by the tests following:— 
[§ Its solution gives with ammonio-nitrate of silver 
a canary-yellow precipitate (Ag' 3 As0 3 ), insoluble in 
water, but readily dissolved by ammonia, and by 
nitric acid. Sprinkled on a red-hot coal, it emits an 
alliaceous odour.] 
Sulphuretted hydrogen passed into a solution of it 
acidified with HC1, gives a yellow precipitate, As 2 S 3 , 
which is readily soluble in sulphide of ammonium. 
Sulphide of cadmium, which is like it in colour, is 
not soluble in sulphide of ammonium. 
To detect a compound of arsenic, whether pure or 
mixed with other matters, a modification of “Marsh’s 
test” is the best. 
A is a six-ounce flask fitted with funnel-tube, and 
containing pure granulated zinc and dilute sulphuric 
acid. The hydrogen produced in A is conducted 
through B, a short wide tube, containing chloride of 
calcium, to absorb moisture from the gas. C is a 
tube of hard glass, which will bear the heat of the 
