Miscellaneous Intelligence. 275 
on general chemistry, and, in indeed, has confined himself to 
narrow a range ; for much might have been added which ter 
and at the same 
interesting and profitable to his readers. Greater completeness 
aR : ing 
of mention, since this salt may, in many cases, well replace the more 
istilled pyro aac s acid neutralized with witherite or 
with sulphid of barium and evaporated almost to dryness, with 
constant stirring, gives a dirty, granulated eer fa which may be 
ve urified by washing it with pretty strong alcohol. The alcohol 
dissolved in water and treated with a little bone eer we obtain 
by filtration a colorless solution, which, on being dried down affords 
a nice white salt. So eae “ei 6a acetate of baryta, that | but small 
quantities of ‘Géibel 6 3 geri washings ; and it 
is not unlikely that the elec rol might ed by wood spirit. 
Of course the aleohol may be recovered by ' dintiliation, and used 
again and again. 
The manufacturer who would carry on his work intelligently 
should know how to determine the strength of his products by some 
way giving more certain indications than the mere hydrometer; 
and the entire omission of everything relating to this matter seems 
to us a defect in the book before us, A ready mode of testing pyro- 
eous acid is a desideratum, for the acid itself assumes a very 
deep color when neutralized, and the common acidimetric method 
depending on the change of litmus, is therefore precluded. Litmus 
is at best but an indefinite indicator of the neutralization of acetic 
trying transparent and light colored it is a good 
plan to add afew drope of of a solution of neutral sulphate of ——— 
and then proceed with the addition of a normal alkali. The least 
excess of alkali gives rise to a B04 opacity in the liquid 
under exubalsiiatban arte i una eon gag impervious to 
light so that even this ailable. Perhaps the easiest 
course would * 
be to ascertain ie In 
crease of specific gravity caused yf acid for some 
scinelt easltata, og ccicipa’ Uf ad careeapoauee 
to every increase of duniity ae no testing whatever should be 
pierre i a. until he has been y in- 
structed in r routine by some one well skilled in 
pea cers Be = Wee were forcibly impressed with this thought by 
an instance that came under our notice a few yearsago. A 
maker having sold a large quantity of his vinegar, warranted to 
