BRITISH SCIENTIFIC ASSOCIATION.

Wanganui Chronicle, Volume 5, Issue 273, 19 December 1861, Page 4

BRITISH SCIENTIFIC ASSOCIATION.

Thi3 .;S®riety held its annual meeting at .'Manchesfer l 'ift September. From l the opening address of the President, Mr. fFairbairn, we make the following extracts :—; THE DEVELOPMENTS OP CHEMISTRY.

The largest developments of Chemistry have been in connection with thb'useful arts. What would now be the condition 'G-f calico-printing, bleaching, dyeing, and even agriculture itself, if they had been deprived of theoretic chemistry ? For examp] a :—-Aniline—first discovered in coal-fra* by Dr. Hoffman, who has so admirably developed its properties —is now ( mocti extensively used as the basis of r.d, blue, violet, and green dyes. This important discovery will probably ID a few years render this country independent of the "world for dye-stuffs ; and it is more than probable that England, instead of 'drawing her dyestuffs from foreign countries, may herself become the centre from which all the world will be supplied. It is an interesting fact that at the same time, in another branch of this science, hi. Tournet has lately demonstrated that the colours of' gems, such as the emerald, aqua-marina, amethyst, smoked rock crystal, and others, are due to volatile hydro-carbons, first noticed by Sir David Brewster in clouded topaz, and that they are not derived from metallic oxides, as has been hitherto believed. Another remarkable advance has recently been r made by Bunsen and Kffrchoff in the application of the coloured rays of the prism to analytical research. We may consider their discoveries as the commencement of a new era in analytical chemistry, froiff the extraordinary facilities they afford in the qualitative detec-; tion of the minutest traces of elementary bodies. The value of the method has been proved by the discovery of the new metals r csesium and rubidium byM. Bunsen, and it has yielded another remarkable result in demonstrating the existence of iron and six other known metals in the sun. In noticing the more recent discoveries in this important science, I must not pass over in silence the valuable light which chemistry has thrown upon the composition of iron .and steel. Although Despretz demonstrated many years ago that iron would combine with nitrogen, yet it was not until 1857 that Mr. O. Binks proved that nitrogen is an essential element of- steel, and more recently iff. Caron and M. Fremy have further elucidated this subject; the former showing that cyanogen, or cyanide of ammonium, is the essential element which converts wrought iron, into steel ; the latter combining iron with. nitrogen through the medium of ammonia, and then converting it into steel by bringing it at the proper temperature into contact with common coal gas. There is little doubt that in a few years these discoveries will enable Sheffield manufacturers to replace their present uncertain, cumbrous, and expensive process, by a method at once simple, and inexpensive, and so completely under control as to admit of any required degree of conversion being ’’obtained with absolute certainty. Mr. Crace Calvert also has proved that cast iron contains nitrogen, and has shown that it is a definite compound of carbon and iron mixed with various proportions of metallic iron, according to its nature. Before leaving chemical science, I must refer to the interesting discovery. by.,.M. Deville, by which ho suooeeded in rapidly melting thirty-eight or forty pounds of platinum —a metal till then considered almost infusible. This discovery will render the extraction of platinum from the ore more perfect, and, by reducing its cost' will greatly facilitate its application to the arts. IMPROVEMENTS IN MANUFACTURES.

I may advert to a fe .v of the improvements which have marked the progress of the manufacturing- system in this country. When Arkwright patented his water frames in 1767, the annual consumption of cotton was about four million pounds weight. Now it is one thousand two hundred million pounds weight—three hundred times as much. Within half a century the number of spindles at work, spinning cotton alone, has increased tenfold ; whilst, by superior mechanism, eaoh spindle produces 50 per-oent. more yarn than on the old system. Hence the importance to which the cotton trade has risen, equalling at the-present time the whole revenue of the three kingdoms, or £70,000,000 sterling per annum. As late a 3 1820 the power-loom was not in existence, now it produces about fourteen million yards of cloth, or, in more familar terms, nearly eight thousand miles of cloth per diem. Mule spinning was introduced by Crompton, in 1787, with about twenty spindles to eachmaohine. The powers of the machine were, however, rapidly increased ; and now it has been so perfected that two thousand, or even three thousand spindles are directed by a single . person. At first the winding on, or forming the she pe of the cop, . was performed by hand ; but this has been superseded by rendering the machine automatic, so that it now performs the whole operation of drawing, stretching, and twisting the thread, and winding it on to the exact form, ready for the reel or shutttle as may be required. These and other improvements in carding, roving, combing, spinning and weaving, have established in this country an entirely new system of industry ; it has given employment to greatly increased numbers, and a more intelligent class of work-people. Similarly , important improvements have been applied to the machinery employed in the manufacture of silk,- flax, and wool; and we have only to watch the processes in these different; departments to be convinced that they owe much to the development of the cotton manufacture. In the manufacture

„<>fworsted, the spinning., jenny was.;not' “employed at Bradford until 17.90, nor th'p power-loom until about 1825. The production of fancy ,or mixed goods from Alpaca and Mohair wool, introduced to this country in 1836, is perhaps the , most striking example of a new creation in the art of manufacture, and is chiefly due to Mr. Titus Salt, in whose immense, pab of industry at Saltaire it, mnyqb©;w oen 0 en in the greatest perfection. In.-flax machinery, the late Sir Pefri- Fairbairn was one of the most successful inventors, and his improvements (have : contributed to the rapid extension of this manufacture.

During the meeting a discussion took place on * artHjLEry and iron-plated snips. Captain Blakely contributed a paper, “ A-rtillery versus Armour.” He described the method of constructing his .description of cannon by surrounding castiron • guns with wrought-iron hoop 3, under a certain degree of tension. He understood Sir William Armstrong was making a 300-pounder gun, but he (Captain Blakely) hoped to make a 600-poun-der, and he did not think there was any limit to the size a gun migHfc be made ; they might go to 60.00 of even 60,000 pouhtiera. He thought that, mightbe done by. coiling wire round / a cylinder. Wire was the strongest form of iron, and they could give the whole mass the required amount of tension. Strength in the longitudinal direction might bo got in various ways. He concluded by referring to what purported to be a table of the pressure of powder in a gun, under several conditions.

Sir W. Armstrong said he did not go so far as Captain Blakely in making great guns. For himself, he thought he should have sufficient difficulty in making a 300pounder, to say nothing of a 60,000 pounder. (Laughter.) He quite agreed with Dr- Fairbairn in the desirability of dispensing with the use of wood in forming the ship. By that they would get rid of the extra weight, and also of the liability of the wood to rotting, and having periodically to pull it to pieces and-rebuild.-' He thought, too, that they should keep in view the adaptation of those ships for a small number of monster gun 3. Plated ships intended to be used against plated ships, must be armed with the most powerful gun 3 that could be made, and if they were too large to be worked by hand, it must be done by mechanical means.

Mr. E. J. Beid (editor of the Mechanics' Journal ) read a very, comprehensive paper “On the iron-cased ship 3 of the British Admiralty.” Mr. Reid then gave some particulars respecting the construction . of the Warrior, the" Black Prince, the Defence, the Hector, the Valiant, <kc. The Achilles, the last laid down, was to be of 6089 tons burden, and to have a speed of from 13 to 14 knots per hour. It was intended to build six such ships in a year or two. The average cost would not be less than <£so per ton, and £'6o per ton per horse-power for the engines. We should then have eighteen iron-cased ship 3, estimated to cost six millions Stirling, but which would probably be nearer eight millions. The inadequacy of our docks for such ships to run into for shelter was then dwelt upon ; it being, shown that in those existing there was not sufficient depth of water for them, while at Cherbourg and other French ports this subject had received attention.

Dr Fairbaih gave the results of experiments ton argets at Shoeburyness. He remarked that our active neighbours the French were building vessels armed with 4 plates ; .and? he was, "One of the committee appointed by the. Fnglisli Government for investigating the sort of plates, with their fastenings, which would be most suitable for covering ships of war and also the quality of the material, so as to find out what presented the greatest resistance to bolts fired at great velocity. It would be the duty of the committee to defeat Sir William Armstrong, who in his turn would do his best to smash up their work. I)r Fairbairn then described the effect of shots upon 5-inch plates, with 18 inches of wood backing. He observed that wherever a shot struck it bent the plates, and the wood being a yielding substance, the plates were indented into it, the latter proving very injurious in breaking the bolts by which the,. plates were fastened. As fastenings they had tried small bolts, screwed l| inches into the in-' oheainto the inside of the plates,, and. leaving the outer surface';-plain. These bolts proved to he too small, and it was proposed to make them stronger, and screw them half into the plates. The 1201 b. shots, flying 11, 000 feet per second a distance of 800 yards, never actually penetrated the five inches, but made damaging indentations. The remains of longitudinal balls were exhibited, of which only a small portion of the striking end held together, the other parts having slided. off all round and broken up. Cast-iron balls, if they, did not penetrate, were smashed to powder. If they could have metal really homogeneous, and build the ships wholly of thick iron-plates, without any wood backing, he thought they would be able to resist the power of even a 300-. pounder gun. Sir John Dairymple Hay, one of the committee appointed with Dr Fairbairn and others to experiment?upon the resistance of iron plates, made, some remarks upon what had been accomplished. The committee had first addressed themselves to finding out the most suitable quality of metal, and his own opinion was that the days of wooden ships were numbered. -• It was pretty certainly determined- ,by the experiments made that the resisting strength of plates increased with the square of their thickness.;, Hence, while the resistance of ;2 inches in . thickness was represented , by. 4, 4 .inches was equal t 0.16 ; and 0 inches thickness gave a resistance of

J -ij- j*. *../■ • ,n '*> V . ; 3ff. _ This was 2 iiiches added to the. 4. Would double ; the resisting power of that due to 4-inch, plates, The Warrior had 4 4-inch plates, backed 18 inches of’ teak. This 18 indm&. of Wood was eaffal in weight to v.early 2 inches; of iron ; but if 2 inches of iron could be. 'added instead of wood making the plates ;.6§ inches thick, they would have dquble the strength of the ; existing plates, He; thought that at any rate the armour plates could be safely made to resist shell, if not shot. " , - .

Sir E Belcher expressed an opinion that small vessels could not carry armour plates, and pointed to * compressed paper as • an excellent elastic material for resisting the passage of a ball. ,