tions and improvements in processes which have yielded interesting products, and in many cases have cheapened the cost of production. In the recent development of technical chemistry the people of Great Britain have done good service, but side by side with the steps which have been taken. by this country in the chemical arts, we have the strides taken by Continental nations, and especially by France, Prussia, and Austria; and in many cases particular branches of technical chemistry have been simultaneously advanced in British and Continental manufactories by similar processes, aud yielding similar results. Continental nations are now fully alive to the national importance of bringing the best knowledge as well as skill to play in the development of the useful arts, and in the production of materials required in industrial pursuits; and there can be no doubt that the peoples of other countries have succeeded in their endeavours to make substantial progress in technical chemistry. The object of the present discourse was merely to indicate in a general manner the services which chemistry has rendered in the working up of natural or raw materials. Sulphur, which at one time was almost solely obtained from volcanic mountains-such as Etna in Sicily-is now very largely utilised from copper and iron pyrites, which contain 40 to 50 per cent. of sulphur. The sulphur smoke in the copper-smelting districts-as in Swansea-which was long destructive to the vegetation of the neighbourhood, and no doubt also to the health of the inhabitants of the locality, is now being made useful, and shortly nearly half-a-million pounds' worth of sulphur will be saved annually. Sulphur is serviceable in gunpowder; in sulphurous acid, the bleacher of wool and silk; in sulphuric acid (oil of vitriol), the most valuable agent in chemical art; and in bisulphide of carbon, which is a ready solvent of oils and phosphorus. The manufacture of bisulphide of carbon is now carried out on an extensive scale; and whilst twenty years ago it cost 25s. per lb., it can now be produced for less than 3d. per lb. This substance is largely used for extracting oil from vegetable seeds, and has latterly been employed in preparing

Greek or Fenian fire, which is a solution of phosphorus in bisulphide of carbon. Unnecessary alarm has been created as to the combustible nature of this substance. No doubt it readily takes fire; and even without a light, when it dries uf, the phosphorus enters into spontaneous combustion. In the event of any of this material being thrown into an apartment, the most ready and effectual means of preventing it drying up and taking fire spontaneously is to pour water upon it from an ordinary can with rose-a little washing soda or, still better, some sulphate of ammonia added to the water will be an advantage, though not necessary. So long as the furniture or other objects are kept moistened with the water, no combustion of the Fenian fire will occur. The scarcity of bones for agricultural purposes has led latterly to great exertions being made to discover other phosphatic substances. Mineral phosphates-as coprolites and apatite—are now largely imported and used. The phosphatic deposits are very extensive in the islands of Sombrero and Navassa, in Norway, at Estremadura in Spain, and in Portugal. Improvements have been suggested on the Continent in the bleaching of cotton and linen, by the employment of permanganates associated with sulphate of magnesia, in place of chlorine or bleaching powder, and the cost of bleaching by the new method is stated to be only three-fourths that of the ordinary or chlorine process. The highly explosive compound nitro-glycerine is prepared by cautiously adding glycerine to a mixture of sulphuric and nitric acids, or to a mixture of sulphuric acid and nitrate of potass (saltpetre). It is a gun-glycerine similarly constructed to gun-cotton. When exploded, one cubic inch of nitro-glycerine expands to upwards of 10,000 cubic inches of heated gaseous products, and hence the material has enormous explosive properties. Bulk for bulk, it is thirteen times more explosive than gunpowder, and weight for weight it is eight times more explosive. It is now used in many places for blasting rock, and its power is so great that one small bore-hole is only required for the nitro-glycerine, where three large boreholes would be used with gunpowder. Water does not in

terfere with its explosion; in fact, the bore-hole may be filled up with water. Blasting cartridges may be made by filling. the cartridge with sand, and thereafter saturating the latter. with the nitro-glycerine. The means adopted, unfortunately, at Newcastle for getting rid of the material, served to charge the ground with the explosive substance. The canisters ought to have been taken out to sea, opened, and sunk there. The nitro-glycerine is liable to spontaneous decomposition and explosion, and ought not, therefore, to be stored in towns, or indeed anywhere in quantity. It can easily be made on the spot where it is required, and only a small amount need be kept in stock. A new mode of manufacture of washing soda has been carried into practice. Steam, accompanied by the vapour of common salt, are conveyed into a tower containing flints or balls of sand, when a silicate of soda is produced, and this may be acted upon. by lime to form caustic soda, or by carbonic acid to produce. carbonate of soda (washing soda). This process will materially aid the working of the Alkali Act, which has already achieved excellent results under the able and conscientious supervision of Dr Angus Smith. When it is recollected that nearly 400,000 tons of common salt are annually decomposed in England for conversion into washing soda, the magnitude of the alkali trade may be observed. In metallurgic processes, the working up of platinum into vessels. where the edges are joined by fusion before the oxyhydrogen blow-pipe, instead of by soldering with gold, has materially added to the strength and durability of those costly vessels ; and the extreme indestructibility of an alloy of platinum and iridium may be observed from the touch-hole of a Whitworth gun having been made of this alloy, and after firing 8000 rounds the metal was as good and durable as ever. In the extraction of gold from crushed quartz or auriferous sand, a substantial improvement has been effected by the employment of sodium amalgam instead of ordinary mercury. The sodium amalgam is formed by adding sodium to heated mercury, and 1-1000th of the sodium in the compound will be effectual, while 1-10,000th has been found

to do good service. Gold quartz treated with mercury simply, or by ordinary amalgamation, yields little more than one-third of the gold it contains, whilst, when worked up by the sodium amalgam, nearly the whole, or fourteenfifteenths of the whole gold are dissolved out, and can be recovered. The manufacture of the coal-tar colours is not now confined to the numberless shades of all the colours of the rainbow obtained from coal-tar products themselves, but numerous processes are at work, and are producing similar substances and colours with the same bright and pleasing shades, and independent of the coal-tar. One constituent of the coal-tar-viz., carbolic acid-has done good service of late. As a crude material, known as dead oil or pitch oil, the carbolic acid is used for preserving timber, and in the manufacture of the best sheep dips. In a semi-rectified condition, it forms the most powerful disinfectant at present known; when purified, it is a valuable medicinal agent; and when treated with re-agents it yields magnificent yellow, orange, and red dyes. The disinfecting properties of the carbolic acid were well noticed at the time of the cattle plague; and fully twelve months ago, the lecturer had trusted solely to its power as a disinfectant in the removal and re-interment of thirty carcases of cattle which had died of Rinderpest, and which the sanitary exigencies of the water supply of Dunfermline rendered it necessary to raise and re-bury in the midst of a pastoral district. So efficaciously did the carbolic acid disinfect everything, that not a single case of Rinderpest was the result of the removal of the carcases of the cattle. The lecturer then referred to Liebig's extract of meat, and its great value as an article of diet; to Liebig's milk for children, which has been far from successful, as in the four cases where it had been administered to children, they all died; to an amusing patent which had been taken out for the production of vital force, and other subjects. The lecture was illustrated throughout by an extensive series of specimens of the various raw materials and manufactured products, and by numerous highly successful experiments illustrating the properties of the

various substances, including the Greek or Fenian fire, and the mode of its extinction. In conclusion, the lecturer urged upon the Society, as representing applied science in Scotland, to do their utmost to promote the great object of technical instruction so apparently deficient in Great Britain. Unless active measures were now taken to diffuse throughout the country a more thorough knowledge of what was being done elsewhere; and still further, unless greater efforts were made to infuse the principles and facts of science into the education of the people, we would have difficulty in keeping our place in the arts aud manufactures of the world. The duty and object of the Royal Scottish Society of Arts was undoubtedly that of promoting the applications of science to the industrial arts, and he had no doubt the Society would continue to be the representative of applied science in Scotland, and would heartily concur in the furtherance of all measures brought forward with the great object of retaining our supremacy in chemical and other arts.

On a Patent Pot Steam Boiler. By R. W. THOMSON, C.E., F.R.S.E., Vice-President of the Society.*

For the smaller class of steam boilers the vertical form has so many recommendations that attempts are constantly being made to render available the great economy of space, cheapness of first cost, and other advantages which that kind of boiler offers; but those good points in all the vertical boilers hitherto devised have been accompanied by drawbacks of a very serious kind.

It has been found that when the boiler is made with an internal furnace, and a mass of vertical tubes, leading from the crown of the furnace to the chimney, two kinds of mischief speedily show themselves. The boiler primes excessively

*Read before the Society, and drawings exhibited, on 9th March 1868. Awarded the Hepburn Prize, value Ten Sovereigns.