[ i66 ] 



of Carrara marble only i grain of water *, and Florian de Belle- 

 vue, who lately has particularly enquired into this matter, fays, 

 marbles contain no water, or fcarce any; and it is of the granularly 

 cryftallized that he fpeaksl):. Dr. Watfon alfo makes the fame 

 remark. 



To tartar vitriolate Bergman has alfo affigned 8 grains of water of 

 cryftallization, whereas when dried even in a heat of 70 degrees only, 

 except it contains an excefs of acid, it retains not even i percent, of 

 water. To nitre he affigns even 1 8 per cent, a quantity fo great that 

 he can fcarce be fuppofed to have meant water of cryftallization. 

 Lavofier, who by profefTion mufl: have been well acquainted with 

 a property fo obvious, tells us on the contrary that it contains little 

 or none, 15 An. Chy. 256. Mr. Keir allows it when not well 

 dried about 2,5 per cent. Wenzel, on the other hand, took but little 

 notice of the water of cryftallization, and his miftakes are not fo 

 confiderable, moft of them independently of the fource of error al- 

 ready mentioned originated from the fuppofition of a fidiiious fub- 

 ftance which he called Caiijlicum, the unheeded decompofition of 

 nitre when ftrongly ignited, and the fuppofition that acids, when 

 the compounds into which they enter are heated to rednefs, either 

 retain no v.^ater or at leaft a conftant and not a variable quantity of 

 it; this is indeed an error inherent in the method purfued by him, 



Bergman 



* Phil. Tranf. 1766, p. 167. % 41 Roz. 94. 



