t 290 } 



its daik colour. The Argillacese, when mixccl 

 with lime, mejt by themfelves, as above-men- 

 tioned (1). When mixed with iron, as in the 

 Boles, they grow dark or black •, and if the iron 

 is not in too great a quantity, they melt alone into 

 a dark (Tag -, the lame happens, when they arc 

 mixed witli iron and a little of the vitriolic acid, 

 as in the common clay, &c. 



5. Tlie Micace^ and Afbeflinae become fome- 

 what hard! and brittle in the fire, and are more or 

 leis refractory, though they give fome marks of 

 fufibility. 



6. The Fluores difcover one of their chief cha- 

 racteriftics by giving a light, like Phofphorus, in 

 the dark, when they are lTowly heated ; but lofe 

 this property, as well as their colour, as foon as 

 they are made red hot : They commonly melt in 

 the fire into a white opaque flag, though fome of 

 them not very eafily. 



7. Some forts of the Zeolites,, a flone lately dif- 

 covered, melt eafily and foam in the fire, fonie- 

 times nearly as much as Borax, and become a 

 frothy flag, &c. 



8. A great many of thofe mineral bodies which 

 are impregnated with iron, as the Boles, and fome 

 of the White Iron Ores, dec. as well as fame of 

 the other iron ores, viz. the Bloodftone, are not 

 attracted' by the loadflone before they have been 

 thoroughly roailed, &c. 



A further digrelTion upon thefe effects is un- 

 neceffary here, their enumeration belonging more 

 properly to the Mineralogy ♦, it is fufticient only 

 to have mentioned the moft common, in order the 

 better to explain the experiments- that are made 

 with the Blow-pipe. 



SECT. 



