484 ON THE MANUFACTURE OF COMPOSITE CANDLES AT CLICHY. 



learned how to utilise it economically. The soap obtained by this 

 operation is of a greyish -white, and of great hardness. In order to 

 separate the fat acids from it, they pound it, and throw it into great 

 vats, lined with lead, where is already to be found the quantity of sul- 

 phuric acid necessary to neutralise the lime ; a pipe heats this mixture 

 by an injection of vapour, and soon a sulphate of lime is formed, drawn 

 by its weight to the bottom of the vat, whilst the stearic, margaric, and 

 oleic acids remain on the surface, presenting the appearance of a pretty 

 thick liquid, of a reddish colour, and of a disagreeable smell. A series 

 of canals, of a calculated inclination, conduct into little flat reservoirs, 

 made of iron plates and disposed on props, one beyond the other. The 

 liquid fills the superior reservoir, that which flows over falls into the im- 

 mediately inferior scale, then into the third, and so on in continuation. In 

 cooling, the matter coagulates, and, drawn lrom the mould, forms a large 

 square of four centimetres in thickness, by fifty-eight in length and thirty- 

 five in breadth. From these squares it is now necessary to withdraw 

 the oleic acid that tbey contain. Chemistry is not competent to perform 

 this task ; mechanism can succeed, thanks to the hydraulic press. But 

 it is not one simple pressure which can obtain this result ; two, three, 

 and even four, are necessary. The first is a cold pressure. The tablets, 

 placed horizontally,, enveloped in coarse woollen stuff, horse hair, or 

 even ordinary hair, called malfils, and separated by plates of iron, are 

 piled up under an ordinary hydraulic press, and compressed as much as 

 possible. A great part of the oleic acid contained between the crystals 

 of the two other acids passes off in a reddish-brown liquid, and descends 

 to the cellars, where we shall find it by-and-by. The cakes, now 

 flattened, still contain a large quantity of the proscribed liquid, as one 

 can judge by the large red spots which mottle them. They then submit 

 them to a final pressure, which should entirely purify them. This 

 pressure, which is accompanied by heat, is effected by means of ingenious 

 machinery, brought to perfection by M. Galabrun. The tablets are 

 placed vertically between horse-hair etrehidelle covered with, a printer's 

 blanket, separated from each other by one of plated iron, composed of 

 two plates supported by props, leaving between them sufficient space 

 for an injection of vapour, which maintains them at about 80°. The 

 hydraulic pressure is made horizontally, and, thanks to the clever in- 

 vention of M. Galabrun, the vapour continues to penetrate between the 

 plates by pipes made of caoutchouc. 



The oleic acid squeezed out runs into the inferior part of the pre- 

 paration, and goes to find that which has deposited itself there in escaping 

 from the cold presses. There they make it pass through felt filters, in 

 which it still leaves a good part of the stearic and margaric acids, which 

 again undergo pressure. The oleic acid, disembarrassed of the useful 

 matters which it contained, is cashed, given up to commerce, or em- 

 ployed in the manufacture of soft soap ; for the Clichy manufactory, 

 like almost all others, possesses an important soap-making department. 



