332 Scientific Intelligence. [Aprit, 
multiple by a whole number of the oxygen in the bases. This is the 
bed of Procrustes, on which he places every chemical analysis ; 
and by the application of the requisite degree of stretching or 
lopping off he brings every one to the proper dimensions. As 
neither the nitrates nor the phosphates can be reduced under this 
canon, it is obvious that it cannot with propriety be made the foun- 
dation of a chemical theory so important as the constitution of the 
mineral kingdom. 
I have lately made some modifications in the atomic theory, 
which have removed most of the anomalies under which it formerly 
Jaboured. These will appear when the new edition of my System 
of Chemistry, at present in the press, is published. But J may 
state here, for the satisfaction of my correspondent, the mode of 
calculation which I am in the habit of following. I consider the 
weight of an atom of the different ingredients in the mineral king- 
dom to be as follows :— 
Silica... 0s ‘inet SB Ate wen pare ta e.ctey ade eee 
WT GNES © oe 3 ol e's ites, Pa Seer e oop) ooo eas 
WIGWUES TA. S frei so Cross oii a> oop mieten 
CGrUGMIAE Nigra otk anole iaaet ais Vero\ohniratwPape a salar eee 
Fils ee ie pea Bie rb a 8 2 ik svt peu fw da aa ura Ge 
MULAN Pers ae papthcter ss é,eie evaleisinpe Bralanere -- 4°000 
Protoxide of nickel ........0.e.00s5 4°3/9 
Protoxide of iron ...... ad Se epe ¢siepethes eee 
Protoxide of manganese ............ 4°500 
Phosphoric acid ......... Pree ie 4:500 
TIE Se regent Ae huatals oem, ie hie a coe 3 OO 
OVS: ci vivtinieus fase 4 wae aces acest GUM 
NSCLOMMAAN -jesiekale isis alesiels aye «yc e ctateie ore OmoeleD 
ProtOxTe Or CETIUI . 6 cs cass weulen oe Ope 
BarytGsn, Soc. oun e cs wee et asc 6) ey eee 
Procure a logarithmic scale similar to Dr. Wollaston’s scale of 
equivalents, and write the names of the different mineral substances 
opposite to the numbers, denoting the weight of an atom of each. 
When the analysis of a mineral is to be examined, bring the quan- 
tity of one of the ingredients, asthe silica, upon the slide opposite 
to the weight of an atom of silica on the rule, then the numbers 
opposite to the quantities of the other ingredients on the slide will 
stand opposite to the weights of the atoms of each or of some 
multiple of that weight, supposing the mineral to be a chemical 
con:pound, and to be accurately analyzed. ‘Thus the number of 
atoms of each constituent is easily obtained; after which our che- 
mical knowledge of the way in which the constituents combine in 
other cases will enable us to state the constitution of the mineral 
with sufficient accuracy, 
With respect to the chemical analysis of a mineral, it is not suffi- 
cient that the analyst be a correct chemist ; he must likewise be a 
skilful mineralogist ; or the specimen examined must be put into 
o 
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