( M8 ) 
2. We have carried out our measurements only witn diamond 
and graphite, and with white and gray tin, as a preliminary investi¬ 
gation showed us, that the allotropic forms of phosphorus were less 
suitable. 
3. Through the kindness of Mr. S. Lehmans of Amsterdam Mr. Louis 
Tas placed ten grammes of diamond (314 pieces) at our disposal. 
We may be allowed here also to express our hearty thanks to them. 
4. Mr. P. Lebeau of Paris sent us a large quantity of graphite, 
made by the late Henri Moissan; on investigation this preparation 
appeared to be very pure. 
As the researches of Lk Chatelier and Wologdine ') have 
shown that graphite assumes a sharply defined specific gravity at a 
certain temperature only when it has been exposed to great pressures 
(according to the above writers enclosed gases are expelled from it 
in this way), we have exposed our preparation to pressures of 
5000—1000 atms., and have not used it until the spec. grav. 
remained constant after repeated compression. 
We made use of an apparatus constructed specially for this pur¬ 
pose, which is reproduced in fig. 1. 
In the steel block B a hole is bored, into which powdered graphite 
is put. In this hole fits the steel piece D, which is pressed down 
through the block A under an hydraulic press. The graphite cylinder 
made in this way may be easily removed from B, if C is unscrewed, 
and may then be pushed from the hole by means of the piece FE. 
5. The white tin, which was used in our measurements, was 
the same preparation that served in the investigations of Ernst 
Cohen and E. Goldschmidt*); the grey tin came from a block of 
Banka tin, which on a former occasion had been kindly presented 
to us by Mr. H. Baucke, chemical engineer *). On investigation this 
material proved to be very pure. By a special investigation we 
convinced ourselves that it did not contain any white tin. 
Determination of the specific gravity. 
6. Our determinations were carried out at 18°,—38°,and—164* 
A. Measurements at 18°.0. 
7. For this purpose we made use of a pycnometer. As graphite 
is not moistened by water, we took toluene as filling liquid. In 
*) G. R, 146, 49 (1908). 
*) Zeitschrift fur physik. Ghem. 50, 225 (1905). 
S J Zeitschrift fur physik. Ghem. 63, 625 (1908), 
