CHINA-WARE. 



193 



Or II) Frill Cornish Stone. 40: Gypsum, 30; Flint Glass, 25; Blue Calx, 6. 



(2) Do. Do. SO; Do. 50. 



(3) Do. Do. 35; Do. 26; Flint Ifi; Bone, 15; Do. S. 



(4) Do. Do. 40} Do, 40; Do. 6 ;F1. Glass, 12; Do. 2. 



This is never glazed, because the heated sulphuric acid of 

 the cauk stone will decompose the glaze j even were it not 

 formed of components in which the phosphoric, arsenic, or 

 borncic acid, was present and ready to affect the acid of the 

 barytes. 



The stonewares of the best kind are thus compounded, and 

 require to be baked in the first ring of the biscuit oven : 



The chemical utensils' body, so important to the students 

 cf analytical chemistry, has not received all the attention its 

 utility demands. The charge is enormously high, compared 

 with that for other wares : yet searely any is found to bear 

 the raised temperature of a wind furnace. The compon- 

 ents (according to the recipes at present used) are : 



To counteract the effects of the different chemical pre- 

 parations on the vessels, ground biscuit china is mixed 

 in the proportion of forty to fifty per cent, with the preced- 

 ing bodies ; but, the addition of six per cent, sulphate of 

 barytes, has recently been proved of the greatest utility. 



Earthenware Bodies. Some previous remarks intimate 

 the want of scientific knowledge on this subject by the 

 manufacturers. To prove that they were not without a good 

 foundation, the following recipes are given from a MS. very 

 recently written by the superintendent of a large manufac- 

 tory : 



1. Black clay, six barrowfuls ; blue clay, four barrowfuls ; 

 cracking clay, two barrowfuls ; when in slip, add six china 

 clay, two one-fourth stone, ten flint. 



2. Black clay, three barrowfuls ; brown clay, two barrow- 

 fuls ; blue clay, two barrowfuls ; corn stone, forty pounds. 

 In slip, to six, add one flint 



3. Blue clay, sixteen pailfuls, twenty-four ounce to pint; 

 China clay, four pailfuls, twenty .four ounce to pint; flint, 

 four pailfuls, thirty-one ounce to pint. 



4. Clay slip, fifty-four pints ; china clay, eighteen pints ; 

 flint clay, sixteen pints. 



In the manufacture of delft ware, a certain proportion 

 of brick clay is mixed with the others, because the addition 

 of oxide of iron among its components, by promoting the 

 incipient vitrescence of the ware, more than compensates 

 for the tint it communicates. Macquer gives these propor- 

 tions: slateclay, fifty ; blue clay, thirty ; brick clay, twenty. 



The appellation delj't ttare, is usually applied to the 

 kind which manufacturers call cream colour, and, from 

 royal patronage, was named queen's ware. Since its first 

 introduction, however, it has undergone very great changes ; 

 and a particular method of ornamenting it, has caused the 

 adaptation of the body to the ornament, in blue printed 

 tvare. 



The components of queen's ware, or cream colour, are the 

 following : 



And, of the blue printed the following : 



The chalky body ware has these components : 



Mr Lakin's recipe is, blue clay, twenty-six; ground flint 

 glass, twenty-six; flint, six; Lynn sand, twenty, six ; bone 

 earth, eight ; composition, eight. 



The Lynn sand, by its very fine grain, supersedes the 

 expense of calcining and grinding flints; and yet some 

 of the manufacturers calcine it previous to its employment. 

 The lime, by promoting the vitrescence of the mass, renders 

 the ware very compact, yet less refractory in high heats ; 

 and hence these chalky bodies were formerly in much re- 

 quest, because less liable to craze. This certainly might be 

 expected, as it is well known that lime renders glass less 

 liable to breakfrom sudden rise of temperature. The Cambria 

 rock and clay, have not yet been so extensively employed 

 as their excellence might have led us to expect, and only 

 because of the disregard of chemical science by the parties 

 who first used them. When this auxiliary is allowed its 

 proper share in the conducting of the processes, the Cam- 

 bria clay will be found one of the most valuable components 

 of British earthenware ; yet obtainable at very moderate 

 expense. 



When proper attention is paid to the proportions of the 

 several components, seldom does any failure occur, and 

 then only in consequence of some intermixture with them, of 

 which the manufacturer was not aware. For instance, a 

 quantity of flint was supplied, which had been ground with 

 a chert that contained an extra quantity of carbonate of 

 lime, and as this was not neutralized by an extra allowance 

 of alumine, the regular heat of the biscuit baking fused most 

 of the ware. Mr Good, Burslem, had ware and saggers 

 fused together, and the fireman was so astonished, that he 

 ran away I 



The greater the quantity of flint which nan be used, the 

 whiter is the ware, yet it must be duly proportioned, else 

 the second baking will cause it to crack ; and, although the 

 weights are determined for the slip makers, an endless va- 

 riety of mishaps result from their blunders of over and un- 

 der flinting. 



The majority of manufacturers are not yet convinced of 

 the bad policy of indulging the caprice of dealers, who, hav- 

 ing paid according to a certain scale of prices, will not rise 

 up to that which will allow a fair profit on a superior kind 

 of ware. Hence, cheapness of production is too much re- 



tarded, and the excellence of the ware injndiciously sacri- 

 ced to economy, in the use of certain components which 

 cost less of themselves, and need less baking ; though it 

 scarcely bears the usage of the warehouseman and packers ; 

 acids and hot water affect the glaze, crazing ensues, and 

 the article is deteriorated, and ultimately discarded. Now, 

 this is no trifling affair, for the worthlessuess of any kind of 

 ware, has 'depreciatory effect, by the stigma on all from 

 that district ; and, in the censures it causes, all manufac- 

 turers are implicated ; it injures them, locally, by suggest- 

 ing the idea of superiority in the manufactures of other 

 potteries ; and it is most prejudical to them, nationally, by 

 the unfavourable comparison when placed in competition 

 with the continent of Europe and China. 



Processes and Manipulations in the Clay. In preparing 

 what is called the body, or by the workmen, the clay, at- 

 tention is indispensable on the part of the manufacturer, 

 that his slip- maker most carefully forms his several com- 

 ments into liquids with water, till the proper density, or 

 ' "ght per ale pint, is formed by adding material or water 

 equisite, as ignorance or carelessness on this point, is 

 often the cause of serious loss. The first method of com. 

 Inning clays, was by placing them stratum over stratum, 

 then exposing them to the action of the atmosphere, and by 

 repeated working with the spade, intermixing them, until 

 they were much disintegrated. After they were continued 

 exposed some months, portions were taken and mixed in 

 water in a square hole, bricked on the sides, with a strong 

 wooden ridge-piece on one edge. This is called the blung. 

 tng pun ; and a btunger is used, formed from a stout a-sli 

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