Cooley's cyclopaedia of practical receipts and collateral information in the arts, manufactures, professions, and trades including medicine, pharmacy, hygiene, and domestic economy : designed as a comprehensive supplement to the Pharmacopoeia and general book of reference for the manufacturer, tradesman, amateur, and heads of families . gas in 1774 prepared the way forthe knowledge of the real composition of air,which was discovered about the same time byScheele and Lavoisier. Scheeles method ofoperating was by exposing some atmosphericair to a solution of sulphide of effec
Cooley's cyclopaedia of practical receipts and collateral information in the arts, manufactures, professions, and trades including medicine, pharmacy, hygiene, and domestic economy : designed as a comprehensive supplement to the Pharmacopoeia and general book of reference for the manufacturer, tradesman, amateur, and heads of families . gas in 1774 prepared the way forthe knowledge of the real composition of air,which was discovered about the same time byScheele and Lavoisier. Scheeles method ofoperating was by exposing some atmosphericair to a solution of sulphide of effected the same object by the com-bustion of iron wire and phosphorus, and sub-sequently by heating mercury on a flask filledwith air for some time, just below its These, however, were but elementary me-thods, which, however creditable to the in-genuity of the great founders of modemchemistry, not only failed in accuracy, but AIR 49 took no account of the presence and amount oftwo most important constituents in the atmo-sphere, viz. carbonic anhydride (acid) andammonia. Determination of Aqueous Vapour. Toeflfect this an aspirator must be used (see As-pieatok). This instrument is easily made,and is not expensive. The accompanying 3 The bottle {a) contains the baryta water. Ithas an accurately-fitting double-perforated. figure will illustrate the arrangement generallyadopted : a is an aspirator made of galvanisediron or sheet zinc. It holds from 50 to 200litres (from 11 to 44 gallons). By this meansa known volume of air is drawn through thetubes marked b, c, d, e, which may be filledwith pumice-stone moistened with strong sul-phuric acid; but if the carbonic acid is to beestimated as well, i and c are filled with moisthydrate of lime (potash used to be employed,but hydrate of lime is to be preferred, as thepotash absoibs oxygen), and d and e as of the tubes is accurately weighedpreviously to connecting them with theapparatus. It is imperative to have each o
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