98 Improved Writing Ink.—Manganefe in Vegetabless 
met with phenomena that foree him to draw very different con 
clufions from them, and to reject the idea of the carbon being 
furnifhed by the decompofition of the carbonic acid; for, in 
fome experiments, he employed for the conealaniae calca- 
reous earth, previoutly deprived of its acid, and excluded the 
contaét of external air, and the refult was caft fteel. Thefe 
experiments. were performed } in crucibles made of Sturbridge. 
clay, without any mixture. Superior effeéts, however, were 
produced-in half the time, by prefenting carbon, in a com- 
paratively deoxydated ftate, in crucibles varioufly compound- 
ed. Some curious queftions naturally arife from the refult. 
of thefe experiments; efpecially from the firft, as, Whence 
comes the carbon? But as Mr. Mufhet has promifed, in 
fome future Number, to Jay his experiments on this inte- 
refting fubject before the public, our philofophical readers 
will then be better enabled’ to enter upon the inveftigation. 
FMPROVED WRITING INK. 
©. Van Mons has applied the difcoveries of Prouft to the 
preparation of common writing ink. He has found that the 
fulphat of iron, calcined to whitenefs, always gives a moft 
beautiful black precipitate. By the following mixture he ob- 
tained excellent ink :—Galls, 4 ozs.; fulphat of iron, calcined 
to whitenefs, 2 ozs.; and two pints of water. The whole 
muft be left ta infufe cold’ for 24 hours; then add gum 
Arabic ro drachiis, and’ preferve it im a ftone jar, either’ 
open,. or covered merely with paper. 
MANGANESE IN VEGETABLES. 
M. Prouft has lately publithed. the following fhort way of 
proving the prefence of manganefe im fuch vegetable produc- 
tions as contain any ;. which has this to recommend it, that 
it is fhorter and more effeCtual than that of Scheele. Put in 
the procefs diftilled vinegar (enaploying heat) on well-wafhed 
afhes, without attempting, however,.to extract from them all 
that they are capable of yielding to the acid. The liquor then 
contains Oxyd of manganefe, lime, and magnefia. Try it by the 
prufliat of pot-afh, and it gives a precipitate of the colour of 
peach blofloms, which, treated by the. blow-pipe in the ufual 
manner, 
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