454 
SUMMARY OF CURRENT RESEARCHES. 
with a little ammonium chloride, evaporated in a round porcelain dish, 
and ignited at a low red heat, till a part of the ammonium chloride is 
volatilised. The fused chlorides are then mixed with cadmium iodide, 
the proportion of these ingredients being adjusted experimentally. 
When the salts are completely fused together, a flux is produced 
which readily enables tin or other soldering alloy to unite perfectly with 
aluminium. The melted flux can be taken up in a pipette with india- 
rubber teat and dropped on to the surface to be soldered. Some powdered 
metallic tin is also sprinkled on the surface. The aluminium is then 
heated over the Bunsen flame till the flux just melts, and is then spread 
with a copper wire or thin glass rod. As the temperature is further 
raised, the flux decomposes, and the tin readily alloys itself with the 
surrounding surface of the aluminium. While the flux is decomposing, 
the tin can be spread in a continuous layer with the glass rod or copper 
wire. 
Instead of cadmium iodide, fused lead chloride may be used. 
Brownian Movement.* — Mr. K. M. Cunningham finds that the 
Brownian movements of particles of magnetic sand are arrested by the 
presence of a magnet. Some fragments of a magnetic fossil wood did 
not show the motion at all. 
* Journ. New York Micr. Soc., xiii. (1897) pp. 64-7. 
