-i 10 



rilKMISTKV. 



[QUALITATIVE A> \ 



solution U to be onnoontraU-I, and at last evaporated to 

 drynou. This should be effected at tho cunclr. 



.v.. by means of a water-bath, lest the basin 

 spaaed to the beat of the flame should on 

 arrangement U easily made, by placing the ev.-< 

 dUh in another of larger ie, filled with Iwiling-wnter 

 and kept at that heat ; or the small dish may be placed 

 on the top of a tin saucepan, the water in which is to 

 be kept boiling. All tho solid substances will tliu 

 be removed from solution ; and if only a very smai 

 quantity of boiling- water be then poured on to 

 the mass, all the substance* will be again dissolved, 

 with tho exception of tho sulphate of lime, which is 

 thus removed from tho mixture. The fluid is then to 

 be poured into a clean test-tube ; more water added to 

 :ning sulphate of lime may be tested as 



(6.) We shaU now have left in the rolution a very 

 minute portion of sulphate of lime (which we may 

 neglect), and the sulphates of magnesia and iron with 

 the common salt. 



The common salt, or rather its chlorine, is first to be 

 removed by means of nitrate of silver, as in Experiment 

 85. The solution must then be cleared of the preci- 

 pitate by means of filtration. 



(c.) The clear solution now only contains sulphate oi 

 magnesia and iron ; and we have to obtain these two sepa- 

 rately. A little hydro-sulphate of ammonia is to be added, 

 when the iron U precipitated as the black sulphide. 



(</.) We have now nothing remaining but the salt of 

 magnesia. The solution having been filtered from the 

 sulphide of iron, is to have added to it some solution of 

 potass, and to be boiled, when the magnesia will be 

 precipitated as a white hydrate. 



Tims the lime, common salt, iron, and sulphate of 

 magnesia, may successively be detected in the manner we 

 have pointed out. 



We have thus given some experiments illustrating tho 

 methods by means of which inorganic substances con- 

 taining earths and metallic oxides may be analysed. 

 Wo shall now proceed to what will be more difficult to 

 the tyro namely, the means we have of detecting tho 

 pretence of alkalies. These substances and their com- 

 pounds are, with few exceptions, soluble in water ; and 

 they therefore cannot be generally detected in the manner, 

 or with tho ease, that the metals are susceptible of. Some 

 of tho salts are more easily detected than others. Thus 

 the nitrates and chlorates of each of the alkalies, deflagrate 

 with burning charcoal, producing carbonates, which may 

 be <li 1 from those of the earths by their great 



solubility in water. The salts of potass give a violet 

 tint in the blow-pipe, tlaino ; whilst those of soda afford a 

 yellow colour. Potass and soda may, however, be dis- 

 : -i of tho chloride of platina and tar- 

 tanc acid. With tho chloride of platina, potass combines 

 and affords a yellow crystalline substance. With tartaric 

 acid, it produces the comparatively insoluble hitartrato 

 of potaw, or cream of tartar. Now soda produces no 

 precipitate with the platina salt, and none with tartaric 

 acid, unless a very concentrated solution be employod. 

 Tli.- chloride of platina also affords a yellow crystalline 

 product with ammonia and its salts. But the latter 

 alkali may always be distinguished by tho smell, which 

 may bo produced by heating its salts with lime or potass. 

 The ammonia in set free ; and if apiece of moist turmeric 

 papor bo 1. ho fumes, it will turn rod a colour 



which U lost as the alkali evaporates. A glass rod 

 moistened with hydrochloric acid, affords white fumes of 

 aal-ammonUc. If a piece of horn or flesh be heat, d, 

 and burnt in a test-tube, and cither of these tests be 

 applied, tho presence of ammonia will at once be made 

 evident. All tho alkalies change the yellow colour of 

 turmeric to red, and restore tho colour to blue, of pre- 

 viously reddened litmus-paper. We advise the student 

 to make repeated experiments with potass and soda in 

 the blow-pipe flame, so that he may acquire tho knack 

 of dUtinguuhing them. He may also watch the < 

 of Uwrir giving colour to tho flame of burning spirits of 

 vine. We may suggest tho following experiments, as 



dated to familiarise tho mind with some of the 

 Appearance ,alies, as met with in ana 



... itt 87. Fuso some sand in a crucible, with 

 four times its weight of carbonate of ]> arate 



the silica as directed in K\pcriment :5, (/) ; but add 

 nitric instead of hydrochloric acid, to dissolve out tho 

 glassy matter. Having filtered the solution from the 

 silica, evaporate to dryness, and take the residue away, 

 throwing it on a piece of red-hot charcoal. I'.y this 

 means a deflagration will take place, and the ch.i 

 and oxygen of the nitric acid forming carbonic acid, 

 carbonate of potass will be produced. Put the piece of 

 charcoal into distilled water, to dissolve away the alkaline 

 carbonate ; and having filtered tho solution, add some 

 cldoride of platina, * The yellow crystalline double salts 

 of chloride of platina and potassium will be produced. 1 n 

 this experiment, three points may be noticed the pro- 

 duction of the carbonate of potass; its easy solubility; and 

 the production of a double salt of platina and potassium. 

 iteriment 88. Ammonia is never met with in what 

 we may term a mineral state, and is always tho product 

 of organic decomposition. Its reaction, however, may bo 

 noticed by adding the platina salt to a solution of sal- 

 ammoniac, when a double salt, analogous to that of 

 potass, will be formed. It has, however, a lighter colour 

 than the potass precipitate. We shall have to give full 

 details as to the detection of ammonia when we treat on 

 organic analysis. 



There is a class of substances often met with in inor- 

 ganic analysis, which may, generally speaking, be obtained 

 from their combinations by means of sublimation. Of 

 these, arsenic and sulphur are the most likely to claim 

 the attention of the student. Any ore containing, or 

 suspected to contain, either of these substances, may be 

 placed, being first reduced to powder, in a test-tube or 

 Florence flask. Heat is then to be applied, when tho 

 arsenic present will sublime as the white arscnious acid, 

 and the sulphur settle as a yellow crystalline substance ; 

 but, if ignited, producing sulphurous acid gas. The 

 sulphides of some of tho metals may be readily analysed 

 by the following method. 



Experiment 89. Take a small piece of galena, the 

 native sulphide of lead ; and having reduced it to powder, 

 digest it in a flask with nitric acid, until tho whole is 

 converted into a white powder. This is the sulphate of 

 lead, produced by the oxidation of the sulphide at the 

 expense of the nitric acid. Occasionally sulphur will 

 3e set free in the solid form, but this is easily recognised 

 jy its general properties. 



Mercury is also a volatilisable body, but will only be 

 met with in those conditions in which its presence will bo 

 easily recognised. The same may be remarked in re- 

 'erence to iodine and bromine. 



( )nr previous remarks and experiments, with tho 

 cables of tests given at page 303, will thus enable tho 

 student to undertake a general qualitative anal\>: 

 most of the substances which ho may ordinarily meet 

 with in inorganic analysis ; and wo shall give a sys- 

 tematic arrangement which is generally applicable in all 

 cases. In this we have interwoven tho plan recom- 

 mended by Frescnius with that which wo have generally 

 adopted ourselves. Wo shall suppose that a great variety 

 of all sorts of compound* may be present, and that each 

 s to be separately eliminated in the course of analv 



h a state of combination cannot occur in nature ; but 

 he plan has the advantages of pointing out tho various 

 i ranees and indications of most of tho compounds 

 which can possibly be mot with in an extended and long 

 .00 in analytical investigation. 



GENERAL PLAN FOR INolIOANIC QUALITA- 

 TIVE ANAL 1 ! 



1. Ascertain, as far as possible, the specific gravity 

 nd other physical characters of the body ; and refer to 

 ho general properties of metals, alkalies, earths, and 

 alts, for general ideas of its constitution. 



-'. Induce, if requisite, to powder. Heat this, and 

 See antr, p. 372. 



