NOTES AND ABSTRACTS IN CHEMISTRY AND PHARMACY. 469 
permanganate decolorized. Fe 4 = Na 0 ,]S ]'03 in decolorizing power. The 
amount of real nitrite of soda in the solution being known, is recorded on the 
bottle. 
A mixture of any bulk is then made in the following proportious :— 
. r Ferridcyanide of potassium 332 grs. \ in | pint of boiling • 
\ Acetic acid (Beaufoy’s) ... 800 grs. J water, 
g/Corrosive sublimate . 164 grs. 1 maj^e up to ^ pint 
^ Solution of nitrite of soda = 80 grs. of true NaONOg J with cold water, 
adding acetic acid, if necessary, until quite clear. Pour the cold solution B into 
the hot solution A. The mixtures becomes at first turbid, but in a few minutes 
afterwards quite transparent. It should be kept at a temperature of 140° (at 
which point little nitrous acid is lost) for some hours, with addition, if neces¬ 
sary, of more nitrite of soda and acetic acid from time to time, until all ferrid¬ 
cyanide has disappeared. When this is the case, the whole mixture may be 
boiled down, until, on cooling, it solidifies to a thick paste. The right state of 
concentration has been attained, when, on beating the paste up, and squeezing 
in linen, a pale syrup, chiefly of acetate of potash, is expressed. The pearly- 
looking mass, freed from acetate of potash as far as possible, must be redis¬ 
solved in such an amount of boiling water, that on cooling, a large proportion 
of cyanide of mercury separates in white pearly scales, quite free from nitro- 
prusside crystals. On squeezing in linen, a deep-red solution of nitroprusside 
is expressed, and a white, pearly mass of cyanide of mercury remains on the 
linen. On concentrating the red filtrate, a large crop of crystals of nitro¬ 
prusside of sodium is obtained in a mother-liquid containing more or less cya¬ 
nide of mercury, in pearly scales, easily separated by throwing the whole on a 
moderately coarse hair sieve, which will retain the prisms of nitroprussides of 
sodium, and allow the cyanide of mercury to pass through. The prisms may be 
washed quite clean by allowing the cyanide of mercury to settle down in the 
filtrate, and using the clear supernatant fluid for washing. The operation can, 
of course, be continued as far it may be deemed profitable. If the cyanide of 
mercury is not wanted as such, it can be made to furnish hydrocyanic acid and 
corrosive sublimate for use again, by boiling with hydrochloric acid. 
It may be added, in conclusion, that nitroprussides react well only with 
monosulphides. The more of a persulphide the solution contains, and the 
deeper the yellow colour, the less distinct is the reaction. This difficulty can 
be overcome by warming the yellow persulphide with sufficient cyanide of po¬ 
tassium to decolorize it, when the beautiful carmine of the monosulphide will be 
obtained. 
Chalk as a Ferment. 
M. A. Bechamp has been engaged in investigating the action of the chalk 
which is generally used in butyric and lactic acid fermentations. Chalk is 
commonly added to a liquid undergoing this change, for the purpose of neutra¬ 
lizing the acids formed, and thereby augmenting the quantity producible. Al¬ 
though this, no doubt, is its general method of action, yet M. Bechamp now 
shows that native chalk is of itself capable of acting as a ferment, and^ when 
added to a solution of starch or of sugar, will establish the alcoholic, lactic, and 
butyric fermentations, without the intervention of any other substance. 
It is well known that the chalk formation consists almost entirely of the fossil 
remains of minute organized beings, which are readily detected by the microscope. 
But independently of these fossils, which represent life which is gone, we are 
assured by M. Bechamp, that white chalk still contains quite a generation of 
living organisms^ much smaller than any we know, and less than all the infusoria 
and microphytes which have been studied in fermentations. These living 
