SCIENTIFIC SUMMAKT. 
429 
clilorine, merely mask deleterious emanations without destroying them. He 
professes to have discovered a means of disinfection which neutralises all 
putrid effluvia. The process can be executed with rapidity, and costs only 
10 centimes per cubic metre. (“Unfortunately,” says the editor of the 
“ Chemical News,” who abstracts the paper, “ no indication is given as to 
the nature of this new disinfectant.”) 
Waterproof Glue. — The “ Chemical News” (August 29) says that bichro-' 
mate of potassa has the, property of rendering insoluble, under the influence 
of light, certain organic bodies, such as gum, glue, glycerin, &c. If a paper 
covered with gum mixed with bichromate is exposed to light, the coating 
becomes quite insoluble even in boiling water. This property is utilised in 
the so-called “ carbon ” photographic process. Strong glue becomes in- 
soluble more rapidly than gum, and the action takes place slowly even in 
the dark. A concentrated solution of bichromate is prepared, which is kept 
in the' dark, and a little of which is added to boiled gelatin. Objects glued 
with this, after some time, can be washed either with cold or hot water. 
Mr. S. J. Mellhuish appointed Photographer to the Shah of Persia. — We 
learn from the “ Chemical News ” that Mr. Mellhuish, F.R.A.S., has re- 
ceived the honour of special appointment as Photographer to His Imperial 
Highness the Shah of Persia; the reason assigned by the Shah for con- 
ferring this honour being that he had never had portraits which pleased 
him so much, although he had sat to artists at St. Petersburg, Berlin, 
and Paris. 
An Improvement in the Manufacture of Gelatin. — M. F. Heuze, who 
describes this method in the “ Bulletin de la Society Chimique ” (of Paris, 
August 5, 1873), says that his object is to obtain white gelatin from pro- 
ducts of low quality. He attempted first to bleach the brown or nearly 
black gelatin, which is obtained as a secondary product in the manufacture 
of neats’-foot oil. This gelatin is applicable to very few uses on account 
of its dark colour, and is sold at 42 francs per 100 kilos. To prepare it, the 
feet — after removal of all parts useful for the turners — are digested in water 
or superheated steam at a pressure of 3 atmospheres. After three hours of 
digestion, and half-an-hour for settling, the strongly ammoniacal solution of 
gelatin is concentrated, the supernatant oil having been previously removed. 
A dark brittle gelatin is thus obtained. The author tried to bleach it with, 
sulphurous acid, or with a sulphate in presence of hydrochloric acid, but the 
results were unsatisfactory. He attempted then to modify the process of 
manufacture itself, diminishing the duration of the action of the superheated 
steam. Instead of drawing off all the liquor at the expiration of three 
hours, it was drawn off three times from hour to hour. The solution was 
then mixed with wood charcoal mixed with 25 per cent, of animal charcoal, 
and after standing twelve hours was treated as above. The solution requires 
4 per cent, of the charcoal mixture. The product is a gelatin of good quality, 
which only presents a yellow tint when seen in large masses. It is tasteless 
and scentless, and is even fit for alimentary purposes. 
A new Mode of Analysis for Rocks is given by M. Fouque, in a recent num- 
ber of the “ Comptes Bendus.” It is briefly as follows : — One to two kilos, 
are reduced to a coarse powder (^ millimetre hi diameter) : the powder is 
divided into two portions, the one for mechanical, and the other for chemical 
