348 
THE ANAL YSIS, 
A 
100 grains of the pulverized substance was heated with 200 grains of caustic 
pot-ash, in a silver crucible. The mass was then dissolved by 12 ounces of distilled 
water, and filtered. 
B 
To the solution a, nitric acid was added, as long as a precipitate formed. It 
was then further diluted, boiled, and filtered. The precipitate obtained dried at 
212®, weighed 126 grains; heated to redness, 110 grains. 
c 
As the precipitate b might contain a small portion of the pot-ash, it was boiled 
with 200 grains of marine acid, diluted, and filtered; when heated to redness, 
weighed 94 grains. 
D 
The filtre of the process a contained no extraneous matter. The solution of 
nitrate of pot-ash b, being completely neutralized, was crystallized; and from the 
mother liquor a precipitate of silex was obtained : weighed 1.5 grain. 
E 
The solution of muriatic acid c was neutralized by carbonate of pot-ash, and 
boiled, and proved free from precipation. 
100 parts of opal wood contain 
Grains. 
Silex .... c 94 , 
^ , r 95.5 
D 1.5 
Loss 4.5 
100 
Anxious to have the presence of carbon, in the opaline wood, still 
more plainly manifested, I again troubled Mr. Pepys ; the result of 
whose obliging and ingenious labours I shall give you, in his own 
words ; only omitting his well-adapted contrivance, for conducting 
his experiment with security and eifect. 
