po + : 
N20 Scientific Intelligence. 
to all who have seen it. The stereoscopic effect is perfect ; vascular and — 
cellular tissues, and mucous membranes are shown in bold relief; anda — 
magnifying power of 200 to 300 diameters can be used with reflected 
light with entire satisfaction. With transmitted light the higher powers 
can be used on suitable objects. 
Note.—There is one defect in this form of binocular microscope, viz, 
object glasses of large angular aperture take in light from so greats 
field that a portion of light enters the branch of the compound body on 
the same side from which it originates. This gives, with low powers, as 
moved to a greater distance from the prism. this defect can be obvi- 
ated, this form of binocular microscope will undoubtedly prove greatly 
superior to all other forms yet devised. M. C. Waite.’ 
New Haven, Dec, 7, 1860. 
received a paten he e-piece consists of a double 
convex field-lens, about three-fourths of an inch thick, and a plano-convex 
| is formed in the solid substance of the field-leus. 
Alumina from Lime and Magnesia.—in the ordinary method of sept ff 
= 
rating alumina from lime and magnesia by means of ammonia, the — 
precipitate of alumina is apt to contain portions of the carbonates of the - 
earths, whic course cannot be removed by washing. To avoid this o 
difficulty, it is only necessary after precipitating by ammonia, to boil 
whole gently until there is no longer any smell of free ammonia. In 
¢ 
manner, the alumina is completely precipitated while the whole of the c 
In this 
carbonate of lime or magnesia is decomposed and dissolved by the ammo — 
niacal salt present. It 1s of course necessary that chlorid of ammonium — 
or some other ammoniacal salt should be present in sufficient quantity. 
The precipitated alumina is very difficult to wash out upon the filter; 
it is therefore better after bringing it completely upon the filter, to dry the — 
whole partially till the alumina has shrunk together and just moistens the — 
paper when pressed against it. The alumina may then be easily and 
seb 
