402 W. Hallock— Chemical Action between Solids. 



Double amplitude magnified 3-3 times =0'5 mm . 



a— 0'08 mm . 



T =0-3 seconds. 



2?ta H T V a 



« = -=-= 1*7. 1= — =36. 



1 a 



This corresponds to about II on the H.-F. scale according to 

 the paper frequently cited above. The intensity was, however, 

 IV or higher. 



Aet. XLII. — Chemical Action betvieen Solids •* by William 



Hallock. 



In a note on a new method of forming alloys published 

 some time ago,f I suggested some additional experiments which 

 I intended to make, and I now give the results thus far obtained. 

 Unfortunately other work prevents my continuing the investi- 

 gation at present. 



Inasmuch as the method and principle;}: seemed well estab- 

 lished where metals were used to produce alloys, an attempt 

 was made to include some chemical reactions in the list. The 

 most natural cases were the freezing mixtures where solid 

 reagents are used. In order to surely have both constituents in 

 a decidedly solid state the experiments were performed in a 

 vessel cooled to a temperature of minus 10° or 12° C, care 

 being always taken to leave the reagents in the vessel long 

 enough for them to assume a temperature decidedly below zero 

 Centigrade. Under these conditions a crystal of rock salt 

 (NaCl) and a piece of clean dry ice were gently brought in 

 contact, lying side by side on a watch glass. Of course the 

 result was a solution of salt, but old as this experiment may be, 

 it appears here in a new connection, as an example of the union 

 of two solids below the melting point of either, but above that 

 of the product. The piece of ice was frozen to the glass and 

 during the operation the crystal was drawn several millimeters 

 across the glass, doubtless by capillarity, as the solution ran out 

 at the bottom of the surface of contact as fast as it formed, 

 the attraction being sufficient to move a crystal several 

 grams in weight. 



Similar experiments were performed with sodium and potas- 



* This paper was read in part before the Phil. Soc. of Washington, D. C, 

 October 13th, 1888. 



f W. Hallock, Zeitschr. f. Phys. Chem., ii, 6, 1888. Science, xi, 265, 1888. 



% 0. Lehmann Wiedemann Ann., xxiv, p. 5, 1885, suggested the theoretical 

 possibility of producing an alloy in this way. I had overlooked his paper until 

 recently. Mr. Lehmann, however, evidently did not consider it possible to fulfill 

 the necessary conditions and did not try the experiment. 



