1S3 On the method of extractimr Saltpetre. [April 



Avith the snnction of Government, for the best mode of producinec 



artificial Saltpetre, and was of much use at the time in dravvino- 



o 



attention to tlie suhject, the result however of many attempts, 

 thouu'h successful, ended in disappointment, as the process was 

 so expensive as hardly to repay the out-lay, by the produce. 



The source from which advantage was to be expected, was 

 th.it ot St eking: for the natural mines of Saltpetre, either in 

 the soil or ia stones, and to collect it from caves, cellars, stables, 

 or sheep firms. 



In the year 17S4 M. Riff\iult was specially deputed by Govern- 

 ment, to instruct the several Saltpetre manufactories in the use of 

 Porasse (one of the most important operations in the manufacture 

 of Salipetre) and to form new establishments in every Province 

 where Saltpetre could be obtained, so that in a few years, the 

 annual produce of pure Saltpetre delivered for the use of Govern- 

 Ton^ about 1872 "^ent amounted to 1,900,000 of Kilogrammes, of 

 sufficient to mak • which Touraine and the neighbouring- country 

 b77oir'oV'Gtr. ^^PPl'^^ Nitrieres, or artificial V^, Paris 



powder of lOOlbs. and the other departments the remaining half. 

 ^^^*^* This last portion ought necessarily to augment, 



consequent to the increase of Territory. 



The following are the processes established in France for the ma- 

 nufacture of Saltpetre. 



The first process is to reduce the material which contains the 

 Saltpetre to such a powder, as that the water will penetrate every 

 part, and dissolve the whole of the salt. 



As in France Saltpetre is chiefly found in calcareous stones, they 

 are broken in a mill, and sifted through sieves, or broken with bea- 

 ters armed with iron and sifted. 



A manufacturer of Saltpetre ought to be provided with an in- 

 stinment called an Areometre for nitre, to ascertain correctly the 

 d -n^ity of solutions. The Areometre of the Administration of 

 France is so graduated^ as to shew, when plunged into a cold sa- 

 line solution the quantity of salt contained in 100 parts of the so- 

 lution : for instance, if the Areometre* when put into a cold saline 

 sohition mark? 15 dec-rees we may be assured that for every 100 



* = think it necesvary lu m; iition here, that there are two descriptions of 

 T^ o; +or n'tre u=ed in France.— First. That of the Administration, 

 which !^ snifficif v'tly explained above, and is the one referred to in this work. 

 - Vf^o, nf'iy. That of Baum6 which is graduated so as to indicate the quan- 

 tity of salt extra to 100 parts of water, so that when it marks 15 degrees, 

 there must be 15 parts salt in solution with 100 parts of water. 



