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ceedingly brittle that it can be easily broken with the fingers. The 
effect of time upon it has resulted in a complete alteration of its 
molecular structure, the mass of the alloy being converted into an 
agglomeration of crystals, and to this its brittleness is due. On 
melting and casting a small fragment I found that the cristalline 
structure disappeared and the metal regained its original toughness.” 
These observations agree so completely with the results so far 
obtained that it was decidedly worth while to investigate whether 
the plate described had been converted into the grey modification. 
5. A dilatometer was filled with 4.8 grams of the material 
derived from the antique vessel. Petroleum was used as measuring 
liquid in the capillary. The dilatometer was placed in a bath, the 
temperature of which rose slowly. The change which occurred was 
shown by a considerable fall of the level of the petroleum in the 
capillary. The fall amounted to 537 mm. 
The white tin had therefore been converted into the grey modi- 
fication. 
The following caleulation shows that the change had taken place 
practically completely. Assuming the specific gravity of white tin to 
be 7.3 and that of grey tin 5.8 the volume of the 4.8 grams, 
containing according to GOWLAND’s analysis 94.35 percent of tin, 
should decrease, in consequence of the change from grey tin to 
white tin, by 
4.8 X 0.943 4.8 X 0.943 
gig EE aia El Be 
5.8 7.3 ar 
The volume of 1 mm. of the dilatometer capillary tube was 
0.00028 cc.; a fall of 537 X 0.00028 ee. = 0.15 ce. 
If the white tin had been wholly converted into the grey modi- 
fication, therefore, the change of volume in the dilatometer experi- 
ment would have been 0.16 cc., that found being 0.15 ce. 
We may therefore conclude from this experiment that the white 
tin in the ancient vessel was practically completely converted into 
the grey modification. 
I have to thank Dr. van DER Puaats of Utrecht for further 
information respecting the mean temperature of the place where 
the vessel was discovered. 
According to BARTHOLOMEW, Physical Atlas, Edinburgh, 1899, 
the mean temperature there is 10° C. The yearly variation of tem- 
perature at the surface is + 12°.2. Under ground it is of course 
