A F F

A F F ( 22 )

that of the base by an integrant number. Someof the experiments we shall mention.

TartaricArid, 100 parts-of this acid welldried, were dissolved in water, and decomposedby acetited lead. The resulting tartrite of leadweighed 235.1. Five parts of this tartrite werethen decomposed by sulphuric acid, and gave4.23 of sulphat of lead, the composition ofwhich being already known, that of tartrite oflead was inferred to be 164.87 oxyd of lead(containing 11.79 oxygen) to 100 of pure tar-taric acid. Hence the 235.1 of tartrite of leadbefore mentioned contained S8.75 of tartaricacid free from water, and 11 .25 of water ; or,(in the same'proportions) 100. parts of puretartaric acid combine with 12.7 of water, con-taining 11.2 of oxygen. As this 11.2 docs notvery much differ from. 11.79, it may thereforebe inferred (making allowance for inaccuracyof experiment) that the water and the oxyd oflead saturating 100 parts of pure tartaric acidcontain the same quantity of oxygen.

Citric Acid. 100 parts of dry citric acid weredissolved in water, mixed with 300. of oxyd oflead, evaporated to dryness and dried for somehours at a heat above boiling water. The re-sidue weighed 379. parts, and hence there wasa loss of water from the acid amounting to20.8.5 per cent. Another 100. parts of thesame citric acid combined with lead from theacetite, as in the foregoing experiments withtartaric acid, gave 237.56 of citrat of lead.Another 100. of the same citric acid heated ona sand bath till it first melted and then'hardened,

but without decomposition, lost 7.0S of water.100. parts of the citrat of lead treated withsulphuric acid, gave 90.56 of sulphat of lead,which contain 66 66 of oxyd of lead, and hencethe composition of citrat of lead is 1. of acid to2. of oxyd of lead. From these data the in-ferences (which need not be gone over at length)are, that 100 parts of mere citric acid saturateas much oxyd of lead as contains 14.13 oxygen :that 100 parts of the crystallized acid contain20.S3 of water, 7.0S of which may be repelledby heat alone, and may therefore be considered aswider of crystallization ; and the remaining13.77 is the water of composition , and theformer is (vyithin a trifling difference) half thelatter. Moreover, 100. of real citric acid willunite to 17,14 of water of composition (whichhere acts the part of a base, as it is expelled onlyby displacing it by the intervention of anotherbase) and this 17.14 of water contains 15 ofoxygen ; and this quantity of acid also combineswith 8.52 water which con tains half this quantityof oxygen. Hence (making large allowance forinaccuracy) the oxygen of the water of crystal-lization in citric acid being taken as 1. that ofwater of composition, and also that of the sa-turating portion of oxyd of lead are each about2. which agrees with the law of compositionlaid down.

Many other saline substances examined by theauthor were found tolerably well to agree withthe above law. For example, 100 parts of cry-stallized sulphat of iron contain the followingelements, viz.

Sulphuric acid — •— 28.9 containing 17.34 oxygen

Suboxyd of iron — — 25.7 — 5.8

Water — — —- 45.4 —- 40.16

therefore the oxygen of each of these threeelements is respectively in the proportion of1.3 and 7.

The author gives many other experiments onthis subject from which he deduces the followinglaw, namely, that in every compound of threeor more oxydated substances, the oxygen ofthat constituent part which contains the leastquantity of it is a common divisor for the otherquantities of oxygen. And where one of thecompounds is water its oxygen is equal to thatof the base multiplied by some integral number.But it does not always happen that the oxygeniu the water bears the same simple ratio to thatof the acid ; though each of them are measuredby a simple multiplication of that of the lowestbase. Thus iu the case just stated, the oxygen

1 Journ. deP

of the water is to that of the base as 7 to 1 ,and that of the base is to that of the acid as 1to 3; but that of the water is to that of theacid as 7 to 3, which is a ratio that cannot beexpressed by an integral number.

ALALITE. See Augite.

ALAUNSTEJN.

A specimen of this mineral was found byKlaproth 1 to contain

55.5 silex

19. alumine

16.5 sulphuric acid

-4. potash

3. water

98.0

Ixxi. 4] 2.