338 PHYSICS. 



Kidder, under Cross's direction, has determined the modulus of elas- 

 ticity and the mopulus of rupture of white spruce wood {abies alba). 

 The pieces were about 1^ inches square and 4 feet long. The modu- 

 lus of elasticity was found to be from 1,000,000 pounds to 1,700,000 

 pounds, depending on the length of time the load was applied, and the 

 modulus of rupture 11,000 pounds. {Proc. Am. Acad., February, 1881, 

 285.) 



Do la Bastie has communicated to the French Academy some results 

 obtained by Thomasset, showing the resistance to flexure of his hard- 

 ened glass. Two series of results are given. The first, including 32 

 tests, shows (1) that the elasticity is more than doubled by hardening; (2) 

 that single glass hardened has 2.5 times the resistance of ordinary 

 double glass, and (3) that semi-double hardened glass is 3.1 times more 

 resistant than ordinary double glass. The second shows that (1) the 

 flexure of ordinary glass is inappreciable, while the hardened glass 

 bends under the strain; (2) that hardened glass polished, varying in 

 thickness from C millimeters to 13 millimeters, had 3.07 times the resist- 

 ance of ordinary plate of the same thickness, and (3) that unpolished 

 hardened glass resists 5.33 times better than unhardened glass. {Ann. 

 Chim. Phys., June, 1881, V, xxiii, 286.) 



C. O. Thompson has investigated the apparent lubricating action of salt 

 as used in wire-drawing, and reaches the conclusion that it is a physical 

 rather than a chemical one, a continuous, adhesive, transparent coating 

 of salt appearing on the wire as it emerges from the draw-plate. The 

 intense pressure to which the wire and the salt are subjected and the 

 high temperature caused by this pressure (a temperature at least as 

 high as the fusing i^oint of tin, 237° C.) cause the particles of salt to run 

 together and to form a complete plastic coherent sheath around the wire. 

 This result the author compares to regelation, a theory tested and 

 proved by submitting salt on the end of a steel cylinder a half inch in 

 diameter to a pressure of 192,000 pounds. During the first experiment a 

 thin, transparent sheet of salt gushed from the side. After the second 

 a transparent, coherent wafer of salt was obtained, through which the 

 mark of a No. 4 Faber pencil could be read distinctly. {Proc. Inst. 

 Min. Eng., February, 1881, ix, 299.) 



Spring has submitted various substances to pressures ui> to 10,000 

 atmospheres, and finds that many weld completely and become crys- 

 talline. Thus bismuth becomes crystalline under a pressure of 6,000 

 atmospheres, and zinc of 5,000 at a temperature of 130° 0. Octohedral 

 sulphur welds easily at 3,000 atmospheres, and becomes crystalline ; 

 prismatic and soft sulphur rapidly becoming octohedral. Manganese 

 dioxide, at 5,000 atmospheres, gives a black mass having the crystalline 

 texture of x)yrolusite. Zinc sulphide takes a saccharoid structure like 

 sphalerite, and lead sulphide, at 6,000 atmosi)heres, resembles galenite. 

 A mixture of copper filings and sulphur becomes crystallized sulphide. 



