Laboratory Manual Of Inorganic Preparations

PREFACE. -- lhe stutly of inorganic chemistry naturally precedes that of organic, and in a certain way this plan is carried out in a complete chemical course. The study of the organic branch, however, proceeds on a much more logical plan than that usually adopted in inorganic work one of the chief advantages being the practical work, to which the student is introduced very early in his course. Ilie following work is synthetic, and she-s how compounds, often very complex in character, rare in occurrence or expensive in preparation, may be producetl from simple substances. or from those which are comparatively plenty and cheap, and at the same time the bye roclucts may be saved. Such a course of study is of great value in inorganic vork, but should 1recede ant1 lead up to, ancl not follow organic cliemistry. Hovever, a contrary plan seems to have been folloived, for while we have various works on organic preparations, there are none, so far as the authors know, in the inorganic branch of the subject at least not in English, excepting the works on Elementary Chemistry ancl vllkre these treat of the sullject in laboratory practice, the methods are those which cannot be recommended as the hest 311d iiost economical. In many laboratories the waste of material is greater than the use. Students are apt to accliire the idea that after a certain result has been produced the rest of the material is worthless, and in consequence much loss occurs from throwing away valua1le substances, which can be recoverecl or usecl with little trouble or expense. It is not a very tlifficult operation to purify the various commercial salts, converting them into C. P. reagents, and in the operation tlle studentcannot help acquiring facts which are directly and forcibly brought to his knowledge. Ioo much reliance is usually 1laced on the so-called C. P. chemicals in common use. Many are high-priced and apt to deteriorate in the LABORATORY MANUAL INORCAN IC PREPARATIONS. LiT A T I R . 11O. 1lre watcr is obttined by tlistilling spri11g -water fi-on1 a copper still wit11 1letd tcl conclenser made of pure tin. The distillation is carried to about tht-ee-fourths of the qlarltity opcl-ated upon. If it is desired to have the clistillcci nrater perfectly fi-cc ti-om carbollic acid and arnmonitrn carIonte, tlie portions passitlg ovei- fii-st must be rejected. In the larKt.1- chelnical laborttories, distilled vater is obtained from tlie steann appartus which serves Iryirg, etc. Iiti vater ccllccted it1 tlic open air may in tiii11 cases bc substitltccl foi- clistillecl watcr-. It mst be colorless, oclol.less, ant1 tasteless, ancl shorild not lertve thC srnallest I-csiclre rllen euapor.lted i11 a llatitum ressel. It shoulcl not he changed bj- arnnonium slphide copl, er, lend, iron, not- I-clclcrccl turbid by baryta water cn1.1otiic acicl, . No clorldiness sllotllcl bc caused e-.en after long stancling by the adclition of a1l1ri1onium osnlatc, of bariulii clloride and lidrocliloric acid sul- 2 LABORATORY MANUAL OF phuric acid, of silver nitrate and nitric acid chlorides, or of lnercuric chloride and sodium carbonate ammonia. We use water principally as a simple solvent for a great variety of substances. If the ordinary distilled water gives a reaction for am- monia with Nesslers reagent, it should be treated with sodium carbonate, about one gram to the litre and boiled until one-fourth has been evaporated.Ammonium free water may also be prepared by dis- tilling water made slightly acid with sulphuric acid. WATER FREE FROM ORGANIC MATTER AND AR.lRfOXIA. About I 5-20 litres of ordinary distilled water, to which about I gram. of potassium hydrate and 0.2 gram. of potassium permanganate have been added are maintained at about looQ C. for twenty-four hours under an...