46 APPENDIX. 



Paris in 1866, when it was seen to become rose-coloured by tlie 

 application of heat, returning to its proper tint on cooling. It 

 is said to be the first instance of such a phenomenon. But, on 

 turning to the 7th Report of the British Association, it will be 

 seen that, in 1837, Sir David Brewster pointed out that the 

 diamond possesses strata of different refractive powers ; and he 

 uses this as a strong argument for its vegetable origin — the 

 changes of refraction, and, consequently, the density in parts 

 and hardness in the same crystal, being due to the action of the 

 gases imprisoned in an expansive mass. 



If we now consider the relations of the diamond to the rocks 

 in which it is found, we shall see how great or how little is the 

 dependence upon them for its origin. 



A statement was made in " Nature," February, 1870, p. 363, 

 respecting the finding of a diamond in granite in the neighbour- 

 hood of Prague. It is described as exceeding in hardness the 

 Brazilian diamonds. It was suggested to be Zircon, but this 

 Dlaschkowitz stone appears to be a veritable diamond. Its 

 occurrence in granite was also mentioned in the Chemical Journal. 

 The statement came from Professor Schafarik, who sent it to the 

 Bohemian paper PolitiJc. On such authority it was received, 

 but not believed as authentic. 



It was not till I found mention of it in an Italian publication 

 that I discovered the mistake that had been committed. In a 

 notice, under the bead "Scoperta di Diamanti in Boeniia,^'' in No. 

 6 of the BoUettino of the Reale Comitato Geologico d/ Italia, pub- 

 lished in June, 1870, p. 175, we read " Fecesi questa scoperta sul 

 finire dello scorso anno nelle vicinanze di Dlazkovic, villaggio 

 posto tra Bilin e Lobositz, in Boemia, dove existe un giacimento 

 di sabbie Granatifere lavorate per 1' estrazione dei piropi, varieta 

 di granato di un bel color rosso. Commista al prodotto della 

 lavatura di queste sabbie, rimarcossi dai lavoratori una piccola 

 pietra sconosciuta, durissima, e di color giallo-verdastro, che sot- 

 toposta ad esame si riconobbe essere un piccolissimo diamante 

 del peso di 57 milligrammi ed in forma di esaedro a spigoli ro- 

 tundati. Dopo di quest' epoca altri diamanti di simil fatta si ri- 

 trovarono, benche assai di rado in quelle sahhie granatifere. Quan- 

 tunque sia questa scoperta di ben poca importanza, pure crediamo 

 bene di segnalarla, essendo indubbiamente questo il primo 

 giacimento diamantifero die in Huropa siasi trovato.''' 



From this we learn that these diamonds were not found in 

 granite but in a garnetiferous sand, which is a new fact for Europe, 

 but not for the supposed origin of diamond in a plutonic rock. I 

 have quoted the original words, to prevent mistakes as to the 

 meaning. 



