96 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
there was no mutual influence between the radiating electrons. The 
divergent, values of the specific separations seem to indicate the existence 
of coupling. F. I. G. R. 
Electro-deposition in Aeronautical Engineering. — W. A. Thain 
[Trans. Faraday Soc., 1921, 16, part 3). Plating has been shown to 
increase the thermal conductivity. Micro photographs are given showing 
the appearance of the deposit in different cases. F. I. G. R. 
Maximum Current Density in Silverplating. — F. Mason [Trans. 
Faraday Soc., 1921, 16, part 3). Manufacturers require that a 
characteristic mirror-like finish should be obtained with a minimum of 
labour after plating. Microscopical investigation shows that this ideal 
condition is largely governed by the size and position of the crystals of 
the deposit. F. I. G. R. 
Failure of Lead Sheathing of Electric Cables. — L. Archbutt 
[Trans. Faraday Soc., 1921, 17, part 1). A very interesting series of 
microphotographs exhibiting cases of incipient intercrystalline fracture. 
An alloy of lead with 3 p.c. of tin has a much finer structure than 
ordinary lead, and seems less likely to undergo intercrystalline failure. 
F. I. G. R. 
Fractures in Locomotive Boiler Tubes. — H. Fowler [Trans. 
Faraday Soc., 1921, 17, part 1). A set of photomicrographs shows 
impurities trapped between the crystal-boundaries, the fractures being 
generally intercrystalline. The tubes concerned were lap-welded. 
F. I. G. R. 
Intercrystalline Fracture in Steel. — D. Hanson [Trans. Faraday 
Soc., 1921, 17, part 1). Several cases have been observed in steel 
boiler plates which have failed in service. The examples given appear 
to indicate that such failure can occur solely as the result of the internal 
or external stresses to which the material is subjected. F. I. G. R. 
Intercrystalline Cracking of Mild Steel in Salt Solutions. — 
J. A. Jones [Trans. Faraday Soc., 1921, 17, part 1). The paper 
describes the action of various solutions of calcium, ammonium and 
sodium salts in producing cracking of steel in a state of stress. 
F. I. G. R. 
Mechanism of Failure of Metals from Internal Stress. — W. H. 
Hatfield [Trans. Faraday Soc., 1921, 17, part 1). Except, is certain 
cases where collective chemical or physico-chemical action causes a 
separation of the remaius of crystals from each other, fractures such as 
discussed in this paner are due to internal stresses introduced during 
manufacture. Important information is given on the subject of rust, 
both in water and in the atmosphere. In all cases the effect proceeded 
indiscriminately over the surfaces, no case of local corrosion at the 
crystal boundaries being observed. F. I. G. R. 
