1886.] 071 Properties common to Fluids and Solid Metals. 407 



obtained by Spring with crystalline metals. Bismutb is, as is well 

 known, very brittle and crystalline, yet fine powder of bismuth unites 

 under a pressure of 6000 atmospheres into a block very similar to 

 that obtained by fusion, having a crystalline fracture. The density 

 of compressed bismuth is 9*89, identical with that of metal which has 

 been fused. The table shows the amount of pressure required to 

 unite the powders of the respective metals : 



Tons per 

 sq. inch. 



Lead unites at 13 



Tin „ 19 



Zinc „ 38 



Antimony unites at 38 



Aluminium „ 38 



Bismuth „ 38 



Copper „ 33 



Lead flows at 33 



Tin „ 47 



We will endeavour to repeat M. Spring's results in the case of 

 bismuth. It is necessary that the powder be perfectly clean and dry, 

 if it be then submitted in vacuo to a pressure of 6000 atmos^Dheres, it 

 will weld into a crystalline mass. 



We know that combinations are produced when certain bodies in 

 solution are submitted to each other's action. But do solids combine ? 

 Is the alchemical aphorism that bodies do not react unless they are 

 in solution, true ? Experiment proves that such solution is not 

 necessary. I have here two anhydrous salts, iodide of potassium and 

 corrosive sublimate, and they are at the same time dry ; when they 

 are mixed together in this mortar, they unite, as is shown by the 

 vermilion colour which is produced. 



My colleague, Professor Thorpe, called attention to the import- 

 ance of this fact at the meeting of the British Association at York, 

 1881. But do solid metals combine in the sense, that is, in which 

 chemical combination is possible between metals, when submitted to 

 each other's action? We know that metals do combine if they 

 be fluid, and the extraction of gold and silver from their ores by 

 amalgamation is moreover easy. It occurred to M. Spring that if 

 there be a true union between the particles of a metallic powder, 

 when submitted to great pressure, it ought to be possible to build up 

 alloys by compressing the powders of their constituent metals, and 

 he urged that the formation of alloys by pressure would afford the 

 most conclusive proof that there is a true union between the particles 

 of metals in the cold, when they are brought into intimate contact. 

 Experiment proved that this reasoning was correct, for by com- 

 pressing, in a finely divided state, fifteen parts of bismuth, eight 

 parts of lead, four parts of tin, and three parts of cadmium, an alloy 

 is produced which fuses at 100^ Cent. It is necessary, however, to 

 compress the mixed powders twice, crushing or filing up the block 

 obtained in the first compression, because the mechanical mixture of 



