372 The Philosophical Society of Glasgow.' 



presence of the mucilaginous matter ali'eady referred to. Molasses, 

 especially if very sour, should be passed through char before being 

 boiled down. 



The power possessed by sugar of combining with common salt and other 

 saline substances, and the property of the salts of preventing the sugar 

 from crystallizing, are matters of which little is known by our refiners, 

 but they constitute an evil of considerable magnitude to the beet sugar 

 manufacturer. The beet sugar that is now imported largely into the 

 Clyde, and which is the thii-d or foui'th crop of crystals, always contains 

 1| to 2h per cent, of soluble salts, and in more than one sample I have 

 foimd as much as 4^ per cent, of nitrate of potash. "When the sugar is 

 refined alone the salts accumulate in the syi'up and communicate to it a 

 distinct saline flavour; but the common custom is to use three parts of 

 muscovado to one of beet. 



[Dr. Wallace occupied the remainder of his paper with a descrip- 

 tion of the methods of manufacturing and refining sugar, dwelling 

 chiefly upon those'details which involved chemical principles, and par- 

 ticularly upon the action of the animal charcoal used in decolourizing 

 the syrup. Specimens of all the varieties of colonial and foreign sugars 

 were shown, and likewise samples of aU the products of the refinery. 

 Specimens of canes from Demerara, drawings of sugar machinery, and 

 Soleil's polariscope for the estimation of sugar, were exhibited.] 



The following Table contains the average results of many analyses of 

 several kinds of raw sugar, as imported into Greenock and Glasgow, and 

 of the diflferent products of a' Greenock sugar-house : — 



Weat Green Oolden 



India. Beet. Date. Lumps. Pieces. Bastards. Syrup. Syrup. Molasses. Treacle. 



Cane Sugar, 94-4 95-7 95-4 97-3 87-7 68-3 627 39-0 48-0 32-5 



Fruit Sugar, 2-2 -3 IS -5 60 15-0 8-0 33-0 18-0 37-2 



Extractive and ColO .3 .^ .^ _ .5 j.g .g 2-8 1-5 3-5 

 ouring Matter,....) 



Ash, -2 1-6 -2 -2 -8 1-5 1-0 2-5 1-4 3-4 



Insoluble Matter,.... •! — 1'7 — — — — — — — 



Water, 2-8 2-0 0-8 2-0 50 14-0 277 227 31-1 23-4 



100 100 100 100 100 100 100 100 100 100 



