30 8 Notices respecting New Books. 



" Diamond Manufacture." 



With a view of ascertaining the behaviour of carbon at 

 high temperatures and pressures, and in contact with a 

 variety of substances, the above experiments were described in 

 a paper to the Royal Society, June loth, 1888. 



These experiments are of interest from the fact that it 

 was found that under certain conditions of temperature, 

 pressure, and substance in contact with carbon hard particles 

 resembling a diamond were produced, which satisfied all the 

 tests for diamond, so far as they could be applied to particles 

 under -^q inch in length. 



At the time of reading the paper a few tests only had been 

 applied to ascertain whether the particles found were veritable 

 diamonds. Shortly after, however, they were examined by 

 Professor Crookes with electrical discharge in high vacua, and 

 appeared to him to behave in a similar manner to diamond 

 powder. 



Tests of specific gravity by immersion of the particles in 

 borotungstate of cadmium and iodide of methylene gave a 

 density of 3*3 to 3*5. 



The particles appeared to consist of two kinds — one irregular 

 opaque black particles, the other translucent plates resembling- 

 flakes of mica, generally of square or irregular shape. 



When placed in a cell in iodide of methylene and projected 

 by an electric lantern on the screen they were clearly seen — 

 the plates appeared to be about ^-J^ inch in length and of 

 extreme thinness. 



On subjecting the powder to the blowpipe all hard particles 

 disappeared, leaving a yellowish-grey residue, but it should be 

 stated that the powder was not previously levigated to remove 

 the lighter portions, which would account for the residue. 



XXIX. Notices respecting New Boohs. 



Magnetic Induction in Iron and other Metals. By J. A. Ewiisro, 



F.R.S., Sfc. Second issue. (' The Electrician ' Series.) 8vo, 



pp. 346. 



TDBOF. EWINGr is such a great and well-known authority on 



■*- Magnetic Induction that it is only necessary to call' attention 



to this second issue of his valuable work to ensure its being in the 



hands of all who require information upon this important subject. 



The book is mostly devoted to a very full and admirable account 



of the researches of the author and of many other authorities into 



the behaviour of iron and other metals when subjected to magnetic 



induction. There is just sufficient theory introduced to enable the 



