110 Scientific Intelligence. 
For sugars suspected to contain grape sugar, and also for molasses 
and inferior sugar, the process is conducted as before ; and next an equal 
quantity of the solution is heated in the water bath to 212°. If nothing 
dissolved in cooling. If glucose is present, the liquid becomes deep 
brown and smells of burned sugar. A second alcalimetric trial gives 
only the quantity of cane sugar which siitcuiaes; the whole of the glucose 
having been converted into acid, which neutralizes the lime in part. 
When liquids are operated upon, it is convenient to have them of the 
density 1-05, or about that of cane or beet juice. They filter better than 
when denser, and dissolve the lime more rapidly than when more di- 
lute. ‘The quantity of lime used should be equal in weight to the sugar 
supposed to be in solution. G. C.8. 
8. Rapid Method of estimating Copper, by means of a Colorimeter ; 
by M. Jacquetarin, (Comptes ne June, 1846.)—A given quantity 
of pure copper, (0°5 grammes,) is diss Ived in nitric acid, an excess 0 
ammonia is added, with pure water, to make the volume. of llitre. 5 
cub. eco of this liquid are put into a glass tube, which is her- 
metically sealed. The color undergoes no change for many months. 
The solution is then made up to a determined volume by the addition of 
water, the color being kept darker than that of the normal solution. 
5 cub. cent. of this liquid are placed in a tube, of the same diameter and 
internal thickness as those of the former. Water is then added until 
the tints are alike. The volume of water being known by a simple pro- 
portion, we can ascertain the quantity of copper in the assay solution 
and in the assay itself. The tints are best observed by placing the 
tubes against a sheet of white paper, and by looking through a small 
hole covered with a blue glass. The use of one eye only is necessary to 
success. 
M. Cassaseca produced a paper on a similar process, at the same 
meeting of the Academy of Sciences ris. G. C. <0" 
9. he Mole animenas the Voltaic Arc; by M. 
Rive, (Comptes Rendus, April, 1846.)—The experiments of the ube 
were made with a Grove battery of ogee irs. The influence ef 
the experiments one pole had the form of a point, the other of a a plate 
and the distance was accurately measured by a screw 
The maximum length of the are between a point and plate. wath 
from two to six millimetres. In case both were of the same substance, 
the length of the are, when the point was in connection with the posi- 
tive, and the plate with the negative pole, was twice as great as when — 
the order was changed. The ‘distance was greatest with silver, iron 
and charcoal, least with platinum. Between different metals, that which 
formed the positive pole, as a point, determined the length of the we 
The plate at the negative pole was however not without influence. 
The intensity as measured by a galvanometer was found to aeenea 
were separated, until the luminous are disappeared. The 
minimum deviation was the same, whatever the nature of the su! 
