( 152 ) 
in his brewery; this is a reservoir through which a current of brine 
passes without interruption the temperature of which during our 
experiments varied between — 7° C. and — 4° C. 
‘The result of the experiments is briefly as follows: (The tin 
employed was part of a block of Banca tin belonging to the 
collection of the laboratory). . 
a. Quite dry, white tin, in the form of a block, was converted 
into grey tin at the temperature mentioned. The process takes 
place slowly and begins at the edges. 
b. Quite dry white tin, in the form of a block, in contact with 
traces of powdered grey tin, undergoes change more rapidly. The 
change begins at the places where the white tin is in contact with 
the grey tin. 
c. White tin in the form of a block immersed in a solution of 
pink salt undergoes more rapid change than the combination 5. 
d. White bloek tin, immersed in a solution of pink salt and 
also in contact with traces of grey tin, is transformed more rapidly 
than c. 
e. When the white tin is exposed to the low temperature in the 
form of filings the process takes place much more rapidly than 
when the tin is in coherent lumps. The velocities of change under 
the circumstances mentioned under a, 4, ¢ and d retain the same 
order as before. 
4. Grey tin, therefore, behaves under all circumstances as if it 
was infectious. If the change is once started it goes on at higher 
temperatures (up to 20° C.). Jt is thus necessary in these investi- 
gations to exercise caution and to take care that traces of grey tin 
are not imported into tin stores, where their presence might, as it 
were, give rise to a tin plague. Grey tin and the finely divided 
white tin formed from it above 20° C. can hardly be fused together 
to a coherent mass, a part becoming useless owing to the violent 
oxidation which it undergoes in the finely divided state. 
5. We have already converted large quantities of white tin into 
the grey modification. In order to attain this result quickly, 500 
grams of tin filings were divided between several bottles and some 
grams of grey tin, which we possessed at the time, were added to 
the contents of each bottle. The solution of pink salt was also used 
in the transformation. At —5° C. a hundred grams of grey tin 
were obtained in this way in eight days. 
6. The destruction of the white tin due to the formation of the 
