450 ’ LEEDS chemists’ ASSOCIATION. 
cooling. Solid caustic soda is said to be much used by the makers of some descriptions 
of paper. 
A few of the new processes for the preparation of soda, deserve notice. The first 
is that for its extraction from cryolite, and in the Exhibition of 18G2 there were 
beautiful specimens of this from Prussia and Denmark. Cryolite (frost-stone) is a 
double fluoride of sodium and aluminium, and it is especially interesting as having been 
the first commercial source of the metal aluminium. It is found abundantly in Green¬ 
land, its previous use by the natives having been for grinding the leaves of tobacco for 
snuff. In this operation some of the mineral becomes detached and levigated, the in¬ 
creased irritating effect being the same as more civilized (?) and crafty manufacturers 
obtain by the introduction of powdered glass. When powdered cryolite is boiled with 
quicklime, insoluble fluoride of calcium, alumina, and caustic soda are produced. 
2nd. By Bicarbonate of Ammonium. —This method was suggested nearly thirty 
years since, and presents the merit of much simplicity in the reaction involved. When 
a strong solution of chloride of sodium is mixed with one of bicarbonate of ammonium, 
the bicarbonate of sodium is precipitated as a fine powder, whilst chloride of ammonium 
remains in solution. By calcination the neutral salt is readily obtained, the carbonic 
acid being utilized at the same time. The salt of ammonium is readily decomposed by 
lime, and its ammonia set free to work out a new cycle of similar decompositions. The 
difficulty of the process consists in the fact that a considerable portion of the chloride of 
sodium escapes decomposition. 
Passing over a dozen other plans suggested, I may glance at the latest patent on the 
subject, viz. that of Mr. Weldon. The patentee introduces into a strong vessel an equi¬ 
valent each of chloride of sodium and of carbonate of magnesium, with some water. 
Carbonic acid is forced in, under pressure, forming bicarbonate of magnesium. By the 
reaction of this salt with the chloride of sodium, it is said that bicarbonate of sodium 
and chloride of magnesium result, the former falling in minute crystals. 
It would not be right to leave this subject without alluding to the fact, that we have 
in Leeds alkaline springs containing from 20 to 30 grains of carbonate of sodium in a 
gallon, and that large quantities of this water are used for various industrial and domestic 
purposes. Since books treating on mineral waters do not recognize such strongly alka¬ 
line waters in England, it becomes more desirable to mention them. 
Potassium Compounds. —In speaking of these as a class, we are struck by the extensive 
substitution of soda or ammonia for potash in many manufactories, the most complete 
being the case of alum, where a period of a very few years has seen the disappearance of 
potassium alum, and its replacement, for economical reasons, by ammonium alum. 
Potassium compounds are, however, essentials for some industrial operations, as the 
manufacture of certain kinds of white glass, gunpowder, etc. 
Now, the production of potassium compounds from their original source, the ashes of 
forest trees, is becoming yearly more restricted in the face-of an increasing demand. 
Fortunately new means of obtaining this essential alkali have lately been pointed out, 
and the Exhibition of 1862 was especially fertile in such developments. 
Firstly. M. Maumene extracts potash from the greasy matter found in sheep’s wool, 
and which is the dried sweat of the animal, being called suint by the French. It forms 
one-third of the weight of merino wool, and though some solid fatty matter is also pre¬ 
sent, the suint may be dissolved out by cold water, and is found to be a neutral com¬ 
pound of an organic acid with potassium. In the woollen manufactories of France, this 
substance is carefully utilized. M. Maumene estimates that the forty-seven millions of 
sheep in France would be capable of supplying all the potash required by her industries, 
whilst at present it is withdrawn from the soil of the sheep-farms, and yet not made 
remunerative to the farmer. 
2nd. Potash from Beet-juice. —M. Kuhlmann has shown how a large amount of 
potassium salts may be obtained from the residue of beet-juice, after the removal of their 
cry stall izable sugar, and the conversion of the molasses into alcohol. In the Exhibition 
of 1862, medals were awarded to both the processes just described, as also to two others 
which I must now mention. 
3rdly. Potash derived from Seaweed. —In the manufacture of kelp on the west coasts 
of Scotland and of Ireland we have sources of potash deserving notice. The seaweeds 
used are practically classed as “ drift-weed ” (^Laminaria digitata chiefly), and “ cut- 
weed ” (various species of Fucus), the value of the former in percentage of potash and 
