VOL. XLII.] PHILOSOPHICAL TRANSACTIONS. SGS 



come to the side of the ship, and there let down likewise between the beams 

 into the places intended ; by which contrivance their operation will not in the 

 least be obstructed, and the tubes be secured from any accident. 



The simplicity of this machine, it being so little cumbersome, its operation 

 without any labour to the seamen, the small expence to put it in execution, and 

 maintain it, besides the before-mentioned considerations, are other arguments 

 for its general use. 



The Method of mahivg Soap-lees and Hard Soap, for Medicinal Uses. By M. 

 Claud. Joseph Geoffrey, of Paris, F.R.S. N° 463, p. 71. 



To make the lye, take, (says Dr. G.) of the best calcined lime, that has 

 been the least exposed to the air, 5lb ; of good salt of kali or glass-wort of Ali- 

 cant, pulverized, and passed through a fine sieve, lOlb. Divide the lime and - 

 the salt of glass-wort, called in England barilla, into 2 equal parts ; then put 

 the lime, broken into pieces not larger than an egg, into new stone pans, and 

 cover it with as much salt of glass-wort as is designed for each pan. Pour, 

 afterwards on these several mixtures hot water, by little and little, to give time 

 to the lime to open itself, till it turns into a sort of meal, which will happen 

 after having poured 3 half-pints * into each pan. Then add to it the rest of 

 the water that is required, stirring this mixture with a stick of white wood ; 

 when there are 18 or IQ quarts of water in each pan, there is enough for dis- 

 solving the salts. In this state the pans are left for 12 or 15 hours; after 

 which this lye is filtrated through brown paper, supported by a coarse cloth, 

 fixed to the 4 corners of the filtering frame. When the whole mass of the lye 

 and of the lime is well drained, put it into a clean iron pot, with 10 quarts of 

 water, to the quantity taken out of each pan, and let it boil an hour ; then 

 filtrate it a 2d time. Afterwards it is put into another clean iron pot, and as it 

 evaporates by degrees, it is filled up again with the first lye prepared, without 

 boiling. Let it continue to evaporate till the 28 quarts of water, that have 

 been used for making the lye of the mixture that was at first put into each of 

 the pans, be reduced to 2 quarts and half a pint, or so long till a small salinous 

 film forms itself on the top of the lye. This liquor turns almost black, because 

 it corrodes the iron ; but this is no inconvenience, as will appear hereafter. In 

 this state of concentration, if we let a drop of it, while hot, fall on a piece of 

 glass, it will be very quickly covered with a fine and greasy film, which makes 

 it look as if it was congealed. At the bottom of this lye is found a salt in flakes, 

 which, being melted in a crucible, produces a lapis infernalis of a strong caustic 



* The Paris pint is near a quart English. — Orig. 



