[ 3M- ] 



SECT. LVI. 



A traveller, who has feldom an opportunity of 

 carrying many things along with him, may very 

 well be contented with this Pocket-Laboratory, 

 and its apparatus, which is fufficient for mod part 

 of fuch experiments as can be made on a journey. 

 There are, however, other things very ufeful to 

 have at hand on 'a journey, which ought to make 

 a fecond part of the Pocket- Laboratory, if the 

 manner of travelling does not oppofe it : this con- 

 firms of a little box including the different acids, 

 and one or two matraffes, in order to try the mine- 

 ral bodies in liquid menflrua, if required. 



SECT. LVII. 



Thefe acids are, the Acid of Nitre, of Vitriol, 

 and of Common Salt. Moil of the ftones and 

 earths are attacked, at leaftin fome degree, by the 

 acids ; but the" calcareous are the eafieft of all to be 

 diffolved by them, which is accounted for by their 

 calcareous properties. The acid of nitre is that 

 which is moft ufed in thefe experiments; it dif- 

 folves the limeftone, when pure, perfectly, with a 

 violent efrervefcence, and the folution becomes 

 clear : when the limeilone enters into fome other 

 body, it is neverthelefs difcovered by this acid, 

 through a greater or lefs effervefcence in proportion 

 to the quantity of the calcareous particles, unlefs 

 thefe are fo few, as to be almofl concealed from the 

 acid by the heterogeneous ones. In this manner, 

 a calcareous body, which fometimes nearly refem- 

 bles a filiceous or argillaceous one, may be known 

 from thefe latter, without the help of the Blow-pipe, 

 only by pouring one or two drops of this acid 



upon 



