F A R JM E R S ' REGISTER. 



615 



in sucli proportions ae one-sevenih to one, or one- 

 third to one-fifth, &c. &c. Uy reflectintr upon 

 these facis, nnd many more vvhicl! mi^ht t)e licre 

 oddiiced, we shall realize the nature of atom?, 

 their indivisibility, and the maihematical nicety in 

 which 6-ulisianct'scliemii'ally cnmbine. This cun- 

 eiilijies the basis ol'ihe x\tomic theory, Trom which 

 chemical equivalents, or proportions, are deduced, 

 rnablinn: the mariulacturin^ chemist to calculate 

 with the i^rcatest exactness, the relative propor- 

 tions of the difi'erenl substances, lie may wish to 

 unite, to liirin tlie recjuircd product, and i;iviiig the 

 analy/:er the power ol'deducing the unknown from 

 the Known. 



These simple substances variously combined, 

 and these combinations variously intermixed, cause 

 the different appearances which are presented to 

 our senses in the vegetable, animal, and inorganic 

 world. By taking advantage of our knowledge 

 ol' the properties which these siniftle substances 

 possess, as well as those to which their combina- 

 tions give rise, we can Ibrm a pretty just conclu- 

 sion of what will be discovered by accurate che- 

 mical investigation. To illustrate — we know that 

 all vegetable substances are fi>rmed of three sim- 

 ples, viz.: oxygen, hydrogen, and carbon, and very 

 rarely a (burih, nitrogen, which is founJ to exist 

 in that product termed gluten, which may be ex- 

 tracted from the germ of wheat, to which add, 

 the comparatively small proportion, of inorganic 

 matter which is found in the ashes. A^ain, 

 animal substances usually contain all the (bur first 

 — I say usually, for there are exceptions to this 

 as to all general rules, as grease or liit, (which is 

 called the grossest part of the animal,) is closely 

 allied to the vetretable oils, and formed of the same 

 substances, neither containinn; the gas nitrogen ; — 

 therefore, so laras the constituents are considered 

 they do not differ. The properties of the substan- 

 ces which Ibrm the mineral kingdom, are not the 

 less distinctly characterized, and by physical in- 

 spection wiili the aid of chemical tests, the ope- 

 rator is enabled to foretell all the constituents 

 which will be found by accurate chemical research. 

 This analysis may be said to commence from the 

 lime an object first arrests attention. 



These facts may appear to some elementary, 

 but I hope on that account not useless, and that 

 they, therefore, may be pardoned by those to 

 whom they are familiar, for the service they may 

 be to others who have less acquaintance with tlie 

 subject. They may furthermore be ofsome utility 

 in enabling some of my readers, the better to 

 comprehend, the one or two examples of analysis, 

 which I shall now add. 



I shall select for the first example, a mineral 

 eubstance, in which we will suppose it desirable 

 to ascertain the quantity of carbonate of lime. 

 The commencement of this operation is its reduc- 

 tion to a powder, (which indeed is the first step in 

 every case,") and this may lie accomplished in a 

 copper, or iron mortarafterwards passing it through 

 a fine sieve. Then, by means of a small sensitive 

 hand balance, weigh say ten grains; by seleciintr 

 a decimal number the calculation will be rendered 

 more easy. This should be placed in a small 

 platina crucible, of a size adapted to the quantity, 

 on a few iirnited coals, and brought to that degree 

 of heat when redness is just becoming visible. It 

 should now be removed from the fire, allowed to 

 cool, and rcweighed. By Eiihs'racling the niirri- 



ber thus obtained from ten, you have the humidity. 

 You now return the powder to the crucible, put 

 oil the cover, replace it on the fire and increase 

 the temperature to a while heat, which should be 

 maintained ibr about fifteen minutes. Suffer it to 

 cool, and weigh. Subtract this from the last num- 

 ber, and it will give the quantity of carbonic arid 

 driven off. It would be well now to ascertain by 

 means of water, and acid, if this last operation 

 has been efi'eciual, and if it has not, it will of 

 course be necessary to rejieat the experiment on 

 another equal quantity, till you have effected this 

 end. Ten giaiiis of the powder should now be 

 introduced into a small glass matrass,* (for these 

 operations those of the capacity of a gill, or half- 

 gill, will be found most convenient,) cover it with 

 water, and add a few drops of muriatic acid, from 

 time to time, keeping up the action till efferves- 

 cence ceases. If the acid be added too rapidly 

 or too much at a time, the action will become so 

 violent as to project a portion of the matter out of 

 the mouth of the vase, in which case it will be 

 necessary to recommence the operation on another 

 like portion. In order to prevent any loss, the 

 safest way is to incline the vase, that the spray 

 may strike the sides. Towards the termination of 

 the operation, the action should be aided by a 

 gentle heat, and any excess of acid should be 

 driven off by evaporation. The solution should 

 now be diluted by the addition of water, and the 

 whole thrown upon a paper filler, (which will 

 retain the insoluble residuum,) and water added 

 till every thing soluble is washed away. In wash- 

 ing, it is belter to allow the water previously added 

 to pass through entirely, before replenishing. If"' 

 the water be hot, the operation will be more ex- 

 peditious. You may ascertain if this is accom- 

 plished by receiving a drop from time to lime, on a 

 piece of glass and drying it over the fire, or in the 

 sun; the washing is completed if it dries without 

 leaving a spot on the glass. 



The filter containing the insoluble residuum 

 should now be carefully removed from its glass 

 funnel, dried, and the matter separated, calcined, 

 and weighed, or as it is scarcely possible to prevent 

 loss in this way, it will prol>ably be more accurate to 

 calcine altogether, burn another filler of precisely 

 the same size, and weigh the ashes, and make 

 allowance for this in the weighing. To the filtered 

 solution you now add lime water, until there ceases 

 lobe a precipitate. Lime being a strong base> 

 will throw down bases of less strength. If no 

 precipitate is produced by the lime-water, there is 

 nothing in solution but lime, and the operation is 

 terminated, and the quantity of lime may be as- 

 certained by the difference between the weight of 

 the insoluble residuum, and the powder which was 

 deprived of its carbonic acid by calcination. But 

 if there be a preci[)ilate, the vase should be 

 covered to prevent the absorption of carbonic acid, 

 (which would unite with the lime and ihus cause 

 an error,) and when se'tlcd, drawn off clear, by 

 decanting, or by means of a small glass syphon, 

 and tlie precipitate collccled on a filter and washed. 

 By drying, recalcining, and weighing, and adding 

 ttie weight of this precipitate to that of the inso- 

 luble residuum, and substracling it from the powder 



* A small vase, technically so called, iniich resein- 

 biins; a FloiTnce flask. Those with Hat liotloms are 

 best. 



