285 



sulphur, " This mineralizing operation is performed by heat or fu- 

 sion ; and there is no person skilled in chemistry, that will pretend 

 to say this m&y be done by aqueous solution*/' 



Professor Playfair, who has given his powerful support to Dr. 

 Hutton's theory, speaking of these substances, metals in the form 

 of an ore, mineralized by sulphur, says, " Their union with this 

 latter substance can be produced, as we know, by heat, but hardly 

 by the way of solution, in a menstruum; and certainly not at all, 

 if that menstruum is nothing else than water. The metals, there- 

 fore, when mineralized by sulphur, give no countenance to the hy- 

 pothesis of aqueous solution : and still less do they give any, when 

 they are found native, as it is called, that is, malleable, pure, and 

 uncombined with any other substance. The great masses of native 

 iron found in Siberia, and South America, are well known ; and 

 nothing certainly can less resemble the products of a chemical pre- 

 cipitation. Gold, however, the most perfect of the metals, is found 

 native most frequently : the others more rarely, in proportion nearly 

 to the facility of. their combination with sulphur. Of all such spe- 

 cimens it may be safely affirmed, that if they have ever been fluid, 

 or even soft, they must have been so by the action of heat ; for to 

 suppose that a metal has been precipitated, pure and uncombined 

 from any menstruum, is to trespass against all analogy, and to 

 maintain a physical impossibility f. 



In a science like chemistry, in which, from the multiplicity of its 

 subjects, and of their operations upon each other, important disco- 

 veries are daily being made, change of opinion must, necessarily, 

 be frequently submitted to, by ^the most intelligent. Hence also it 

 happens, that apparently established theories, of the most learned 

 men, are sometime subverted by those whose general knowledge 

 in the science is much less considerable, but whose application 



* Theory of the Earth, vol. i. p. 63. 



t Illustration of the Huttonian Theory, p. 58. 



