liable to run into acidity than a syrup of the same strength, made from that which has been refined. It therefore becomes an object of importance, as well in the manufacture of raw sugar in the colonies as in its refining, to ascertain the nature of those hurtful ingredients, and by chemical means to effect their separation without injury to the saccharine grain. I do not consider it necessary for the description of my invention to enter here, upon the general composition of cane juice or raw sugar, but will confine my remarks to those substances which are peculiarly injurious, and the separation of which I effect. The juice of the cane and a solution of raw sugar contain two sorts of impurities, the one chemical, and the other mechanical (that is to say), the latter being merely floating particles of bruised cane held suspended in the fluid, it is possible to effect their separation by a mechanical operation, and by such it is usually done; but the former being actually dissolved and in intimate union, can only be extracted by a chemical action, and it is to those impurities, for which no means of separation has yet been devised, that this part of my invention relates; and this I accomplish by the addition of certain substances hereafter to be described, which combine with the chemical impurities of the cane juice or raw sugar, form with them an insoluble compound, thereby reducing them to the state of mechanical impurities, which it is possible to separate by means of filtration. The one which is the most abundant of those chemical impurities, approaches in its nature to what is called by chemists extractive matter; the others are tannin and gallic acid, which I have discovered to exist in cane juice and raw sugar. Those substances possess the property of forming insoluble compounds with the salts and oxyds of tin and zinc; and this part of my invention consists in the addition addition of a certain portion of those ingredients to the cane juice or saccharine liquor in refining, thereby improving the colour and facilitating the crystallisation of the sugar. The solutions of tin or zinc, in any of the acids, possess the property of coagulating these impurities; but I prefer such as contain the sulphuric acid, on account of its forming an insoluble compound with lime; which enables it to be entirely separated from the liquor along with the oxyd, in combination with the extract tannin and gallic acid. And I further prefer for this purpose the solution of zine in sulphuric acid, which constitutes what is called the sulphate of zinc; and in order that the method of using it may be fully understood, I will here describe the operation: First, in the refining of sugar; and Secondly, in the manufacture from the cane. In the former process the pan is to be charged with strong lime water, and the sugar added to it in the usual manner, and the fire set; for every hundred weight of sugar used, a solution is to be made of four ounces of sulphate of zinc in as small a quantity of water as it will conveniently dissolve. When the sugar in the pan is entirely melted, the solution of the sulphate of zine is to be added, and the whole well stirred. A mutual decomposition will then take place, the oxyd of zinc will combine with the extract tannin and gallic acid used, and render them insoluble; and the sulphuric acid will be neutralised and precipitated in the form of sulphate of lime by the lime of the water, so that nothing whatever of the sulphate of zinc, remains in solution. There is in the lime water employed for dissolving the sugar, a quantity of lime more than sufficient to neutralise the sulphuric acid of the sulphate of zinc; but when the raw sugar employed contains much acid, and a strong grain is required, I take one |