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most quantity of oxygen with which they canunite, and thus by proper data to estimate theproportion of these constituent parts, and ofoxygen, existing in the substance analyzed.The substance selected to oxygenate these ele-ments is the oxymuriat of potash, and the mat-ter to be analyzed is mixed with this salt anddeflagrated in an apparatus contrived for thepurpose, consisting of a thick glass tube set ver-tically in a lire with a lateral tube to conduct thegenerated gasses to a mercurial trough, and acock above, the stopper of which is not perfo-rated, but contains a small depression, into whicha portion of the material to be analyzed is put,and by turning the cock downwards, this portionfalls into the heated tube, and there deflagrates.The proportion of the oxymuriat requisite toburn completely the substance analyzed is foundby previous trials in an open crucible, so muchof the salt being required, that the residue afterdeflagration shall be quite white, or at least notcarbonaceous ■, and in the actual experiment aconsiderable excess of the oxymuriat is em-ployed. The materials are then accuratelyweighed (after being long 'dried at a boiling-water heat) and mixed in a mortar with a littlewater to an adhesive mass, which is divided bybeing thrust into a brass mould, and the piecesare rolled up by the fingers into little balls thatthey may drop clean from the stopper of thecock down into the deflagrating tube. Theseballs are again dried at the same heatbefore using.

The oxymuriat of potash is previously ana-lyzed by itself in a proper apparatus to ascertainthe proportion of oxygen which it furnishes, andto ensure an uniformity in this agent a consi-derable quantity of the sail is fused and then rub-bed to powder by itself and kept for use. If thesubstance to be analyzed is a vegetable acid, itis combined with lime or barytes before mixturewith the oxymuriat; and this calcareous-or ba-rytic salt is separately analyzed, and the carbo-nic acid that remains united with the earth afterdeflagration is properly estimated.

The earthy or other incombustible matter be-longing to the substance to be examined is alsoseparately estimated by calcining this substanceby itself in a platina vessel and lixiviating theresidue. The author gives at length all the pre-cautions required in the management of the ap-paratus, both in preparing for the deflagrationand in the estimation of the gasses produced.These last are supposed to be only carbonicacid, azote, and oxygen, the quantity of theoxymuriat being more than sufficient to convertinto water all the hyd.ogen of the substance

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analyzed. The probability of a little carbu-retted hydrogen that may have escaped combus-tion is also acknowledged, and some allowanceis made for it though apparently not in a veryaccurate way. The examination of the gasseousproducts of the deflagration is therefore thusconducted : 200 measures of the gas (standingover mercury) are added to 40 measures of purehydrogen, and detonated by the electric spark.By this means the excess of oxygen is separatedin the form of water, and the quantity of thisexcess is, of course, one third of the volume ofthe entire absorption after the electrization.The carbonic acid is absorbed by potash, andthe residue is further examined for oxygen bythe same means, and the ultimate residue is con-sidered as azote. The data therefore fromwhich the results of the analysis are made outare these : the proportion of combustible mat-ter in the substance examined is previously foundby calcination of another portion of the same ;the actual quantity of oxygen employed in thedeflagration is known bv that of the oxymuriatused ; the carbonic acid is absorbed by potashand its carbon estimated ; the excess ot oxygenis found by subsequent detonation with hydro-gen; the hydrogen of the substance is presumedto form water with all the oxygen unaccountedfor ; and the azote exists in the residual azoticgas.

Fifteen vegetable substances were analyzed inthis way, the particulars of some of which weshall give, and the results of the whole at theend of this article.

Sugar. 1000 parts of white sugar candy, ex-posed for many hours to a boiling water heat,lost only 8 parts of moisture. Some of the'same sugar when calcined left only t -~t °f resi-due. The quantities used for the experimentwere 300 parts of sugar (exclusive of the mois-ture and insoluble residue) and 7 times as muchoxymuriat of potash, the oxygen of which was627 parts (by weight). This oxygen was re-covered, all but two parts, in 449.9 parts of car-bonic acid containing 322 of oxygen, and in anexcess of 303. of oxygen discovered by detona-tion with hydrogen. Therefore the 300 ofsugar had in fact only consumed 322 of oxygen,all of which went to form carbonic acid, ofwhich the carbon was 127.4; and as no other,product from the sugar but carbonic acid andwater appeared, it would follow that sugar iscomposed of 42.47 per cent, of carbon, and57.33 of water, either as such, or of oxygen andhydrogen in the exact proportions required toform water.

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