A C E
A CE
C 2 )
was reckoned at 87.125 per cent. A mixtureof the same acid and water in a certain propor-tion was made, which had exactly the samespecific gravity, but its saturating power wasonly equal to 118 of carbonat of soda, or 58.725real acid. A further addition of water to thislast acid diminished the density as well as thesaturating power, and this continued uniformlyin every subsequent proportion of water added.
On the other hand the first addition of waterto the concentrated acid of 1.063 sp. gr. en-creused the specific gravity, though the pro-portion of real acid was of course diminished.
Hence there must be a point of the maximumof specific gravity in which the gravity wouldbe lessened both by encreasing and diminishingthe real strength of the acid as measured by itssaturating power. This maximum of densityM. Moilerat estimates at 1.0791 sp. gr. and67.256 per cent, of real acid.
The observations of M.Derosne, M.Bertholletand Mr. Chenevix, which we shall presentlymention, confirm this fact of a maximum den-sity existing in this acid in a certain state ofdilution. These observations however only ap-ply to the acetic acid or radical vinegar ob-tained from some of the neutral acetates. Thecommon distilled vinegar contains a quantityef carbonaceous matter which can only be sepa-rated by combining it with a basis and redis-tilling it.
Mr. Chenevix c has given a valuable experi-mental essay on acetic acid and some of theacetates. A quantity of acetite of copper wasdistilled per se, and the product separated as itcame over into different portions. The firstportion had the specific gravity of 1.0659, andthe proportion of real acid estimated from itssaturating power was 62.971. The second was1.058 sp. gr. and 67.461 acid: the third, 1.0454sp. gr. and 74.411 acid ; the fourth, 1.040 sp.gr. and 73.295 acid.
Though these numbers do not exactly cor-respond with those of M. Moilerat, they shewthat the specific gravity of acetic acid is no in-dication of its strength in real acid, and thereason of this is supposed to be the admixtureof a portion of an inflammable spirit in variousproportions formed during the distillation ofthe acetites, which has been examined by va-rious chemists, and which the author termsPyro -acetic Spirit; and M. Derosne, Pyro -acetic Ether.
The products of the distillation of the metal-lic, alkaline and earthy acetates differ remark-
• An, Cbim. tom. 69,
ably in the proportions of the acid, pyro-aceticspirit, and gasseous products, though the ace-tates themselves are all prepared with the sameacetic acid. Hence it becomes an interestingenquiry to examine what is the action of thesebases on the acid during distillation, which canexplain this great difference in the products.The analysis is complicated and attended withmany difficulties, but the experiments of Mr.Chenevix on this subject deserve notice. Themetallic acetates examined were those of silver,copper, nickel, lead, iron and manganese. Agiven quantity of ea.ch was distilled from aluted earthen or glass retort according to theheat required, to which was attached a tubu-lated matrass to collect the liquid products, aWoulfe bottle holding a solution of pure ba-rytes, and a pneumatic trough. The heat waskept up as low as possible to effect the decom-position. The results consisted therefore ofthree substances which required a subsequentexamination, namely, the metal or metallic oxydleft in the retort, the liquid, and the gasseousproducts. The metallic residue was regulinein some cases and oxidated in others, and mixedwith a small portion of charcoal which wasseparated by dissolving the metal.
The liquid product was examined in relationto its specific gravity, its acidity, and the quan-tity of pyro-acetic spirit. The force of aciditywas measured by the quantity of a solution ofpure potash saturated by a given portion of theacid. It was more difficult to separate the pyro-acetic spirit. When alcohol is mixed with anywatery liquid, the usual mode of detecting it isby the addition of carbonate of potash, butwhere the liquid also contains an acid whichby union with potash forms a salt soluble inalcohol, this mode of separating the spirit willnot answer. It was therefore necessary in thepresent instance to redistill from potash theliquid products of some of the acetates, andthus deprive them of their acid, before the spi-rituous portion could be obtained. We shalladd the results of these experiments as far asconcerns the liquid product in the three cir-