1844.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



2or 



but much, as Mr. Smith particularly insisted upon, depends upon the situa- 

 tion of the beds from which the stone is raised : the remains of Koche Abbey, 

 for example, and the church at Tukhill, both built with the stone which Sir 

 C. Wren distinguished as second only to Portland, are in a perfect state with 

 all the sharpness of the mouldings preserved, whereas buildings in the neigh- 

 bourhood erected with the same material during the present century, but 

 without due regard to the choice of the beds, are already in a state of decay ; 

 so also with regard to the Barnham Moor stone, many Roman remains at 

 York are in a far better condition than the works of the middle ages in that 

 city, not excepting the cathedral, and others at Hull, Beverly, and Tadcaster, 

 built with the same stone. The Cadeby stone is found to decompose rapidly ; 

 a specimen used in London, perished in about fourteen years, and yet this 

 stone is found within a short distance of Conigsburgh Castle, which was budt 

 with a similar stone from an adjoining hill, and remains the most perfect 

 specimen of masonry of its age existing in this climate. The characteristics 

 of durable magnesian limestone are its compactness and high crystallization ; 

 those which appear earthy, and powdery, and leave white on the lingers, on 

 being handled, are not to'be trusted. The Anston quarries, which supply the 

 stone for the Parliament Houses, were left to be the subject of a final com- 

 munication. 



At the annual general meeting held May 6, Earl De Grey was re-elected 

 President — Vice Presidents, Messrs. Papwortb, Kendall, and G. Smith. 

 Honorary Secretaries, A. Poynter and G. Bailey.— Honorary Secretary for 

 Foreign Correspondence, T. L. Donaldson. 



ROYAL INSTITUTION. 



April 27. — " On the Recent Researches in Electrical Decomposition." — 

 By Dr. Miller, of King's College. 



The lecturer, after showing by experiments that liquids when conveying 

 the current are capable of extricating heat and inducing magnetism, and in 

 these respects resembled solid conductors, proceeded to state that they differ 

 from solids in the motion which their particles visibly exhibit ; he asserted 

 that most liquid bodies capable of transmitting the current consist of two or 

 more chemical elements in combination, and that when subjected to the in- 

 fluence of a voltaic battery they are decomposed ; one portion of the elements 

 accumulating at one pole of the battery, whilst the other portion collects at 

 the opposite pole. Water, he remarked, had always been considered one of 

 the substances most easily thus decomposed : yet he showed that a spark 

 may be obtained under water from two charcoal points forming the poles of 

 a batterv, of nearly as great brilliancy as that produced by bringing them in 

 contact in air, which is admitted to be an extremely bad conductor; he also 

 interposed at one point of the circuit a small quantity of distilled water, and 

 showed that no electricity passed ; on adding a solution of sulphate of soda 

 to the distilled water, immediate decomposition ensued, and abundance of 

 gas was extricated, an experiment from which he inferred that the presence 

 of a little saline matter confers conducting power upon the water. After re- 

 calling attention to the discovery of Dr. Faradav, that the power measured 

 at any one point of a voltaic circuit is a measure of its force at any other 

 point, so that the proportion of a substance decomposed at one point is a 

 measure of the quantity capable of being decomposed at any other point in 

 the same circuit, he stated, that when saline solutions were electrolyzed. an 

 apparent exception to this law was observed, and the current appeared in this 

 case to have twice the power ; so that a proportion of the salt was decom- 

 posed, and at the same time gases from the decomposition of an equivalent 

 quantity of water were set free, whilst a voltameter included in the circuit 

 only indicated sufficient electricity to decompose either the salt or the water, 

 not both. This apparent paradox he explained by stating that the salt alone 

 is in any case decomposed, and that the decomposition of the water is an 

 accidental circumstance. All salts, he said, might be considered as composed 

 of a metal, or something tantamount to a metal, in combination with a sub- 

 stance or group of substances possessed of equal but opposite electric power 

 (in contradistinction to the common notion that they consist of an acid and 

 a base in chemical union). When subjected to the decomposing action of 

 the battery, the metal, he said, appeared at one pole, while the whole re- 

 maining elements were transferred to the opposite pole ; when the metal, like 

 potassium, was capable of decomposing water at ordinary temperatures, gas 

 was given off, consisting of pure hydrogen, an oxide of the metal was formed, 

 while at the other pole oxygen was given off from its separation from the 

 bodies in combination with which it was transferred under the influence of 

 the current, at the same time, an equivalent of acid was set free ; when, on 

 the contrary, the metal, like lead or copper, was not capable of decomposing 

 water, no hydrogen was extricated, but the metal itself was deposited in tlie 

 solid form. Experiments were shown in proof of this assertion, the salts 

 being in some cases dissolved in water, in others melted by heat alone ; when 

 melted nitrate of silver, for instance, was thus treated, the metallic silver was 

 obtained in beautiful crystals. After adverting to the value of the voltaic 

 battery as a powerful means of investigating the molecular grouping of com- 

 pound bodies, and aiding in the examination of disputed points in theoretical 

 chemistry, the lecturer concluded by describing some curious results ob- 

 tained relative to the transfer of the bodies disengaged under the influence 

 of the current, and by stating that, contrary to the usually received opinion, 

 such transfer did not take place in equivalent proportions in opposite direc- 

 tions ; but that some substances, on the contrary did not appear capable of 

 transfer at all ; among this number was copper, and he referred to this cause 



the impoverishment of the solution around the electrotype plate where the 

 process is long continued. 



May 3. — " On the appUcatiott of the Microscope to Geological Research." 

 By Dr. Carpenter, F.R.S. 



Dr. Carpenter pointed out how much the progress of science depends upon 

 the perfection of the instruments employed in the observation of its pheno- 

 mena ; and that even to geology, whose facts are for the most part obvious 

 to the unassisted senses, the achromatic microscope has afforded, of late 

 years, the most efficient aid. He noticed the researches of Messrs. Witbam, 

 Nicol, and others, on the structure of fossil woods, and the light which these 

 had thrown on the origin of coal. The investigations of Prof. Owen on the 

 structure of teeth were next glanced at, and illustrations of their application 

 to the determination of fossils were given. The identification of the Laby- 

 rinthodon as the gigantic Batrachiaa, whose footsteps are preserved to us in 

 the sandstone of the Stourton quarries, was noticed as one of the most in- 

 teresting results of this kind of investigation ; and a sketch was given of the 

 train of reasoning by which Prof. Owen has established the true character 

 and habits of the Megatheroid quadrupeds. Dr. Carpenter then gave a sum- 

 mary of the researches, on which he has been himself engaged, on the struc- 

 ture of the shells of the Mollusca, Crustacea, and Echinodermata. With the 

 aid of highly-magnified dehneations, he explained the ceWH/nc organization of 

 the shells of Pinna, and other allied genera belonging to the family Margari- 

 tace^, by which the fossil forms of that group are at once distinguished (even 

 by the examination of the minutest fragment) from all others; — the very 

 curious plicated membranous structre, which is characteristic of Terebratula 

 and its allies, and distinguishes them from all others ; — the true character of 

 the lines upon nacre, to which its iridescence is due ; — and the tubular 

 structure, analogous to the dentine or ivory of teeth, which is found in cer- 

 tain other genera, and is distinctive of them. After describing the peculiar 

 cancellated structure of the shells of the Rudistes, and stating that, by his 

 microscopic test, the perplexing Cardium /libernicum should be referred to 

 that group, he briefly explained the structure of the shells of the Crustacea, 

 the inner portion of which is tubular, and strongly resembles dentine, whilst 

 its surface (beneath the horny structureless epidermis) is covered with a 

 layer of cells, in which the colouring-matter is deposited ; and gave a brief 

 account of the structure of the shells, spines, &c. of the Echinodermata, 

 pointing out the difference in pattern between the stems of different species 

 of Pentacrinus, which rendered the microscope a very easy means of distin- 

 guishing them. The lecture concluded with a notice of the researches of 

 Ehrenberg on Fossil Animalcules ; of which the sdicions remains form a 

 large proportion of the chalk-marls of Southern Europe, besides abounding 

 in other deposits ; whilst the calcareous species make up a great portion of 

 the chalk itself in many localities. Of these species, whose minuteness is 

 almost inconceivable, many of those now living appear to be identical with 

 those which existed at the early part of the tertiary epoch. 



May 10. — Lord Prudhoe, President in the Chair. 

 " On the Chemical and Mechanical processes, and the social influences of 

 the Penny Post." By Rev. John Barlow, Sec. R. I. 



Mr. Barlow said that he took this subject because it exhibited one of those 

 instances where immense mental labour, ingenuity, and applied science were 

 required to produce the most familiar articles of common use. The notion 

 of separating, by a system of stamps, the financial department of the Post- 

 office from the transmission and delivery of letters, originated with Mr. C. 

 Whiting, fourteen years since. This gentleman has been rewarded by the 

 government for the taste and mechanical skill exhibited in the method in 

 which he proposed to adjust his plan to the penny-rate adopted at the re- 

 commendation of Mr. Rowland Hill. With tliis notice of the history of 

 letter-stamps, Mr. Barlow entered on the manufacture of the adhesive label. 

 These are executed by Messrs. Perkins, Bacon, and Petch, on Mr. Perkins's 

 principle of steel engraving by transfer. The process depends on the pro- 

 perty of iron to become hard or soft as it receives or loses a small quantity 

 of carbon. This was demonstrated by experiment ; and the description of 

 the process was illustrated by the exhibition of hard and soft steel rollers, 

 plates, and impressions furnished by Messrs. Perkins & Co. Mr. Barlow laid 

 great stress on the absolute identity of every engraving, however numerous, 

 produced by this method. He then observed, that the engine-work on the 

 adhesive labels is of so close a pattern that it cannot be taken off by litho- 

 graphy or any similar contrivance, while on the other hand, the eye is so ac- 

 customed to notice sUght differences between one face and another, that the 

 most skilful imitators of a minute engraving of a human countenance (as 

 that of the Sovereign on the label) could not possibly avoid such a deviation 

 from what he was copying as would ensure the detection of a forgery. Mr. 

 Barlow next adverted to the qualities of the coloured inks with which the 

 labels are printed. Though sufficiently permanent to withstand the effects 

 of sun-light, rain, Sec, they would be discharged by any fraudulent attempt 

 made to remove the obliterating stamp, for the purpose of issuing the label a 

 second time. The gum used for fixing these labels to letters, Mr. Barlow 

 described as being probably derived from potato-starch, and therefore per- 

 fectly innoxious. The manufacture of the postage envelope is effected by 

 many powerful, yet accurate machines. The paper is pervaded by coloured 

 threads as a security against fraud. Wlien sent from the manufactory of 

 Messrs. Dickinson, it is delivered to the firm of Messrs. De la Rue. It is 

 there cut into lozenges by the engine of Mr. Wilson. One of these was ex- 

 hibited, and its power contrasted with that of the old bookbinder's plough. 



18* 



