258 Scientific Intelligence. 
13. ee Balitnce for measuring the Intensity of Cur- 
rents ; by M. Cu. Méne, (Comptes Rendus, Jan., 1848.)—A_ horse- some 
of soft iron is eins a certain number of times with an insulated wire 
the armature is attached to a counterbalanced scale pan. The inte 
of the current is directly measured by the magnetic force developed. 
If the same sort of wire is used, the apparatus may be made more del- 
icate by using a greater number of turns. 
The peculiarity of this method is, that the weight supported, divided 
by the number of turns, represents the influence of one 
wi e, that is, the intensity of the current. The recorded experiments 
shew a tolerable degree of accuracy’ in the results. G. C. 5. 
14. On ec properties of Iodine, Phosphorus, Nitric acid, $c. ; 
by M. Niép E Saint Victor, (Ann. de Chim. et de Phys., Jan., 
1848. \—The ouber has discovered that iodine has the property of attach- 
ing itself to the black lines of engraving, printing, writing, &c., and not 
at all to the white part. On this is founded a process for copying en- 
gravings, &c. The design is exposed for a few minutes to the vapor 
of iodine, and after moistening it in water slightly acidulated with sul- 
phuric acid, it is applied to paper coated with starch paste, on whic 
the copy is most accurately traced. ‘These impressions are of course 
rather fugitive, and may be preserved for some time by securing them 
Several copies may be made without a second preparation of the 
pe ta oe the latter proofs thus taken are the clearest 
rs that all kinds of marks and drawitig may be copied, pro- 
vided. um nape not enter into the writing or drawing material. For 
India ink and lead pencil marks, it is advised to plunge the design into 
a very slight solution of ammonia and then another of avid; before ex- 
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opal, glass very &c., when covered with dirot size, gave 
poised of far greater beauty and permanence: they should when dry 
var 
An elliot engraving when pressed upon a silver plate, without 
being moistened, leaves a very clean copy, which exposed to mercuria 
vapor in all respects resembles the daguerrian proofs. Sbpper plates 
require ammooiacal vapor to bring out the image, which may be clean- 
ed by a little water and tripoli without being removed. 
The black parts of a feather exposed to iodine vapor were a 
copied while the white of the same feather was unmarked. Pieces of 
whitewood and ebony fastened oyether and the face dressed so as to be 
perfectly uniform, in like manner gave a copy of the black alone. j 
e vapor of phosphorus enlarging slow combustion, produced 
the same effuct, the copies on metal being fixed by mercury or am- 
monia. 
Ni tric acid vapor gave renewed effects, the Phites on metal being 
Solutions of iédin ne were found to answer as pre as iodine i 
goulphuret of arsenic (orpiment) in vapor afforded copies on metal w ich 
