1 44 Royal Irish Academy. 



alloy hot into cold water, and then cold into hot water. In this 

 way, if 



W and t = the weight and temperature of the water, 

 M and t' == the weight and temperature of the metallic alloy, 

 m .... = the mean temperature of both, 

 S . . . . = the specific heat of the alloy, 

 there are two values, one where the metal is the hotter, 

 s _ W(m-t) , 

 M (t'—m) ' 

 and another where the water is the hotter body, 

 a _ W (t-m) 

 M {m-t')' 

 the mean of which is the specific heat of the alloy pretty exactly. 

 The result gave the specific heat of the normal alloy = '0879, water 

 as unity, and that of the anomalous alloy = '0848 ; both of which 

 are below the specific heat assigned by Dalton to brass. 



The normal alloy is malleable, flexible, ductile, and laminable. In 

 the anomalous alloy there is an absolute negation of all these pro- 

 perties. 



The normal alloy readily amalgamates with mercury at common 

 temperatures ; the anomalous alloy will not amalgamate with mer- 

 cury even at 400° Fahrenheit. 



When the anomalous alloy is heated to incipient redness in a 

 glass tube, a minute trace of water, and of a burned organic sub- 

 stance, probably adherent oil, are discoverable ; it suffers no change, 

 however, but a slight increase of density. The normal alloy suffers 

 no change when so treated. The normal alloy, treated on charcoal 

 with the blowpipe, fuses at once into a bead. On treating the 

 anomalous alloy so, the fragment swells rapidly to more than twice 

 its original bulk, on becoming bright red-hot ; it then glows, or be- 

 comes spontaneously incandescent, in the way that hydrated oxide 

 of chrome and some others do, and instantly contracts to less than 

 its original bulk, and becomes a fluid bead, which, on cooling, dif- 

 fers in no respect from the original alloy. 



The anomalous alloy, when pulverized in an agate mortar, forms 

 a black powder, devoid of all appearance of a metal ; its filings also 

 are quite black ; while those of the normal alloy, produced by the 

 same file, possess the usual metallic lustre. These facts, in con- 

 nexion with the black colour and fine earthy appearance of the frac- 

 ture, bring to mind the case recorded by Sir David Brewster, of a 

 piece of smoky quartz, the fracture of which was absolutely black, 

 and yet was quite transparent to transmitted light, and whose black- 

 ness, he found, arose from the surfaces of fracture, consisting of a 

 fine down of short and slender filaments of transparent and colour- 

 less quartz, the diameter of which was so small (not exceeding the 

 one-third of the millionth - part of an inch), that they were inca- 

 pable of reflecting a single ray of the strongest light. In describing 

 this, Sir David Brewster predicted that " fractures of quartz and 

 other minerals would yet be found which should exhibit a fine down 

 of different colours depending on their size." 



