Though Dr Black never himself published any account of his peculiar opinions respecting latent heat, they soon came to be generally known all over Europe, in consequence of the great concourse of students from all quarters that attended the chemical class at Edinburgh. Various dissertations both respect ing latent heat, and the capacity of bodies for heat, were published at different times, and in different places. The authors seldom or never refer to Dr Black ; but tacitly assume to themselves the merit of originality. And, in consequence of Dr Black's in dolence and carelessness, it is now almost impossible to deterMine how far these claims were well or ill founded. That Dr Black was the original disco verer, and that he had taught the doctrine publicly, at least ten years before any competitor appeared, is perfectly established. But whether the subsequent authors derived their information from students who had attended Dr Black's class, or had stumbled themselves upon the theory which they published, it is now very difficult to say. The first publisher on the subject was Mr Wilcke of Sweden, whose dis sertation on the capacity of different bodies for heat, appeared in 1773. Lavoisier and Laplace published their experiments on the heat necessary to melt va rious bodies, and upon the heat evolved during com bustion about the year 1777. Mr Cavendish, in a
dissertation published about the year 1785, claims as his own the discovery of latent heat ; but says in a note, that he understood that Dr Black teaches a similar doctrine. As to the attempt of De Luc, in his ideas sur la Meteorologic, to claim the original discovery of latent heat, it does not seem entitled to any attention whatever ; and has been sufficiently exposed by Mr Watt and Professor Robison. Mr Cavendish, from the character of the man, and the great sagacity which he possessed, would be the most likely to have hit upon the theory. But it became so generally known, and so much had been written upon it before his claim appeared, that it is impos. sible to doubt that he had imbibed his opinions re specting heat from these publications ; and certain opinions respecting heat being adopted, the doctrine of latent heat followed as an easy consequence. Up on the whole, Dr Black's originality admits of no doubt ; and had he published an essay on the sub ject, as he did with regard to fixed air, no competi tor whatever would have appeared ; and his rank as a discoverer, at least among the chemists of the con tinent, would have stood higher than it does at