VOL. XV.] PHILOSOPHICAL TRANSACTIONS. 183 



the salts only of mixed bodies thus baffle the force of fire, but the simple ones 

 much more, as being more homogeneous ; as we see in the decrepitation of 

 common salt, and exsiccation of vitriol ; which, when the aqueous parts are 

 once evaporated, are now a pure simple homogeneous body, no longer sensible 

 of the fire, the decrepitation ceasing, and nothing remaining that can be dilated 

 any further to break the corns of salt. Now whatever the fire cannot dilate it 

 cannot separate, nor consequently destroy, or carry any thing from it ; except 

 what is heterogeneous, and accidentally adhering to the outside of it, which 

 is perfectly the case of our incombustible linen, whose threads being altogether 

 homogeneous, and nothing else but the pure striae of liquid alum, holding no- 

 thing of sulphur, bitumen, or water, or any thing that is different or hetero- 

 geneous from itself, that can be dilated or separated, it is in no possibility of 

 being liable to the fire, which may indeed pass through it, as we see it does 

 when made red-hot, but can carry nothing from it. 



Short Memoirs for the Natural Experimental History of Mineral JVaters. By 

 the Hon. Robert Boyle, F.R.S. London, l684-5, Qvo. N" 172, p. ]063. 

 The author divides this tract into 6 sections, the first whereof is only intro- 

 ductory, wherein remarking the imperfect ways in which such waters have 

 hitherto been described, he therefore has thought fit to communicate these his 

 memoirs, in order to a more full and methodical history of mineral waters ; to 

 the drawing up of which he thinks these three following observations necessary. 

 1st. That a man ought to take notice of those particulars that relate to it, whilst 

 it is yet under ground, or in its native receptacles. 2dly. To examine the pro- 

 perties and other qualities of it, when it is drawn up by men at the spring head, 

 or other receptacle. 3dly. He is to consider the operation and effects of it on 

 human bodies, whether sick or sound, &c. 



To the first of these he has subjoined a set of titles for the 1st part of the 

 proposed work. He has given likewise a scheme of titles for the 2d part ; but 

 because the 2d part is that which he mainly designed, he has reserved to it two 

 other sections, viz. the 4th and 5th. In the first of which he gives experimental 

 remarks on the way of examining mineral waters by the help of galls. He can- 

 not by any means think the infusion of galls to be of that use and certainty, 

 that it is commonly presumed to have, inasmuch as it only discovers a liquor 

 to be or not to be, either of a vitriolate or ferruginous nature ; for there are 

 divers metalline ores, and other mineral bodies which, not participating of iron, 

 will not by this means be discovered, and yet may at the same time strongly 

 impregnate the water. The decoction of arsenic, for example, changes no more 

 upon galls than would common water. Moreover, unless iron be the only pre- 



