1875.] Physics. 407 
in the same direction upon the free pole of the magnetic needle, causing it to 
be displaced towards one of the helices according to the direction of the current. 
TrecHNoLocy.—A Board has been appointed by the Government of the 
United States to determine by actual tests the strength and value of iron, steel, 
and other metals which may be submitted to it, or by it procured, and to pre- 
pare tables which will exhibit the strength and value of said materials for con- 
structive purposes. It has standing committees on abrasion and wear, on 
armour plate, on chemical research, on chains and wire ropes, on corrosion of 
metals, on the effets of temperature, on girders and columns, on metallic 
alloys, on physical phenomena, on steels produced by modern processes, &c. 
Th. Schlésing, in a course of studies on arable soils, has examined the in- 
fluence of the salts present in a soil upon its openness of texture. Mould 
stirred up in water subsides the more rapidly the more salts are present, 
especially those of lime and magnesia. This phenomenon, which amounts to 
a coagulation of the clay, is thoroughly examined. The best precipitants for 
clay are caustic lime and the lime salts. 
A good cement for marble and alabaster may be obtained by mixing 12 parts 
of Portland cement, 6 parts of slaked lime, 6 parts of fine sand, and x part of 
infusorial earth, and making up into a thick paste with silicate of soda. The 
obje& to be cemented does not require to be heated. It sets in twenty-four 
hours, and the fracture cannot be readily found. 
M. C. H. Viedt has experimented on aniline inks. Fora red ink he recom- 
mends a solution of i part of “ diamond fuchsin” (we should say of Brooke, 
Simpson, and Spiller’s rosein) in 150 to 200 parts of boiling water. Fora blue, 
he dissolves r part of bleu de Paris in 200 to 250 of water. For a violet, 
I part of a Hofmann’s violet (blue shade) in 300 of water. A beautiful green 
ink is made by dissolving 1 part of iodine green in 100 to r10 parts of boiling 
water. The yellow aniline inks are not recommended. These inks are not 
fit for copying, but they have the advantages of drying quickly, and of never 
clogging. 
Prof. J. Nessler points out that genuine wines contain chiefly malic acid. 
Free tartaric acid is very rarely found, except in spurious concodtions. As a 
test the author uses a solution of 5 grms. acetate of potash, 5 germs. alcohol, 
and 25 grms. water. If an appreciable amount of tartaric acid is present, this 
test produces a crystalline deposit of tartar in a quarter of an hour; whilst, in 
genuine wines, even if they contain a trace of tartaric acid, no precipitate 
appears until some hours have elapsed. Genuine wine contains no citric 
acid. For its detection in small quantities, the wine is rendered alkaline and 
filtered, acidulated with acetic acid, mixed with chloride of barium, filtered, 
and a few drops of ammonia added to the filtrate until it has an alkaline 
reaction. If, on the addition of baryta water, a white precipitate appears, citric 
acid is present. Oxalic acid gives a white precipitate if lime-water is added 
in such small quantities that the liquid has still an alkaline reaction. Sulphuric 
acid in genuine wines is found only to the extent of 0°03 to 0°05 per cent. 
When soluble gases are highly diluted with those which are insoluble, 
their complete absorption is a matter of difficulty when attempted by drawing 
the mixture through simple columns of the absorbent liquid, owing to the 
protecting effect of the particles of insoluble gas. In such cases, and with the 
ordinary wash-bottle arrangement, complete absorption can only be effected 
by greatly multiplying the pieces of apparatus. Mr. N. Glendinning has 
arranged a new form of apparatus, of which the annexed is a drawing. It 
consists of a bottle capable of holding 20 fiuid ounces, which is provided with 
two tubes passing through a perforated india-rubber bung. The tube which 
has to convey the gases to the apparatus has a bore of about ,3,ths of an 
inch, and reaches to within half an inch of the bottom of the bottle. The 
other tube is about 12 in. long and 1 in.in diameter. One end of this tube 
is closed, but is provided at about half an inch from this end with twelve or 
fifteen small holes distributed around it, forming a ring, the holes being equi- 
distant from the end of the tube. The other end of this tube is fitted with a 
VOL. V. (N.S.) 3F 
