SCIENTIFIC SUMMARY. 
203 
and T have for some time been using what might he called a compromise 
vessel, made of platinum lined with gold ; not platinum gilt, but made 
in the following manner: — A thick sheet of platinum is taken and the 
requisite amount of gold melted on the surface ; the whole is then rolled out 
to the proper thickness for capsules and crucibles, and these latter vessels 
then made out of this sheet. There was some little difficulty attending 
the making of the first vessels, but this was entirely overcome in the 
establishment of Johnson, Matthey & Co., Hatton Garden, London, where 
the vessels I use are made.” 
Certain Chemical Mattel's found in Snow. — In the u Comptes Rendus ” 
(Jan. 4), M. G. Tissandier says, u that in the snow which fell between 
Dec. 16 and 25 last, he distinguished the presence of an abundance of foreign 
substances, including certain salts. The dry residue from the evaporation 
of a litre of snow-water was determined. Snow collected in a court yielded 
0-212 grms. ; from the towers of Notre Dame, 0-118 grms. ; and from the 
country, 0-104 grms. The residue obtained on the evaporation of snow is 
.an impalpable greyish powder, of which the organic matter, rich in carbon, 
burns brightly. The residual ash amounted to 57 per cent, in Paris, and 61 in 
the country. It consists of silica, carbonate of lime, alumina, chlorides, 
sulphates, nitrate of ammonia, and very appreciable amounts of iron. He 
suggests that a portion of the matter suspended in the air may have a cosmic 
origin. 
Analogies between the Escape of Gases from Supersaturated Solutions, and 
the Decomposition of Certain Explosives. — M. D. Gernez concludes from his 
experiments that there is the strongest analogy between the escape of a dis- 
solved gas, taking place on the surface of the solution into a gaseons 
medium, into which the gas passes as into a rarified atmosphere, and that 
decomposition of explosives which cannot, as in the case of oxygenated 
water, be ascribed to a particular catalytic force. — Vide “ Comptes Rendus,” 
Jan. 4. 
Remarks on Maltose. — It would seem from a paper in the tl Berlin 
■Chem. Gess.,” that Herr Schulze has re-investigated and con- 
firmed the statement of O’Sullivan that the action of malt-extract 
upon starch produces, not dextrose as had been supposed, but a compound 
sugar having the formula 0 12 H 22 0 U , which he called maltose. The sugar 
reduces the copper test only two-thirds as actively as dextrose, but pos- 
sesses a much better rotatory power. Schulze’s experiments were con- 
ducted with diastase, precipitated from malt-extract by alcohol. Starch 
ymste treated with this, at a temperature of 60°, w T as rapidly saccharified. 
After concentration and precipitation of the dextrin by alcohol, the solu- 
tion was evaporated to a syrup treated with alcohol, the clear solution 
poured off and evaporated over sulphuric acid. Crystals first appeared on 
-the walls of the vessel, and finally the whole solidified to a crystalline 
mass. Becrystallised from water or alcohol, maltose retains crystal water, 
which is readily given up at 100°. In appearence, maltose resembles 
dextrose, but is distinguished from it by its composition, its reducing 
q>ower, and its action on a polarised ray. By boiling with dilute acids it is 
■converted into dextrose. It is therefore an intermediate product between 
dextrin and dextrose. — See “ Silliman’s American Journal,” Feb. 1875. 
