[■ xr J 
advantage, wlien more knowledge In that matte# 
is obtained : But thus much we certainly know 
By experience, that the mineral kingdom is ex- 
tremely well adapted to be examined by thefe 
means. The experiments made by the inge- 
nious Mr. Homberg, with Tfchirnhaufen’s 
Burning-glafs, may certainly be carried yet 
farther, whereby fome doubts may likewife be 
removed, which ftlll remain regarding fome of 
the effeits of his experiments. Thus,, we 
fliould be employed in obferving the phoeno- 
mena and drawing conclufions from them, in- 
ftead of only fearching for the principles of 
thofe effects, as naturalifts were formerly obliged 
to do. 
How fatisfied would every lover of fyftems^- 
be, if by this means he could get materials 
properly prepared to compofe a better work, ia 
which he could introduce the few valuable 
things which are to be found among the old 
ruins, and leave out all the vague expreffionSj;^ 
together with the diftindtions, that are of 
confequence. 
When I had, for the above-mentioned pur- 
pofe, colleded my own obfervations, and thofe 
of others, I heard of tv^o new books on the 
fame fubjed ^ they were Mr. D’Argenville 
Orydology, and Mr. Juflfs Mineralogy 5 for 
which reafon I laid my manufcript afide, un- 
til I had, by the perufal of thofe two works, 
convinced myfelf that thofe gentlemen had not' 
prevented me from purfoing my plan for, 
the former has, in my opinion, endeavoured to 
bring 
