Page:The Building News and Engineering Journal, Volume 22, 1872.djvu/519

 June 21, 1872. THE BUILDING NEWS. 497 the relative proportions of lime and clay may vary within very wide limits. This material, therefore, with the rough appliances available in places of small populations, is generally the best suited for the ob- jects in view; and for the information of those who know little or nothing of it, I may add that the eminent builders, the Messrs. Lucas Brothers, who have usel it very largely, state it to be ‘‘so good, and the saving of time in the use of it so great (as it is equal to any cement at the cost of ordinary mortar), we feel sure that it only requires to be known to be appreciated.” * Selenitic mortar, as is known probably to most of you, owes its remarkable properties to the influence which is exerted upon lime by a small percentage of sulphuric acid intimately mixed in the form of sulphate of lime at the time the mortar is prepared. ‘This treatment en- ables lime to set as cement by depriving it of its ten- dency to swell when combining with water, and to detach itself from the surface to which it is applied. In the case of sewage-made hydraulic lime, with twenty-five to thirty-five per cent. of clay present in the calcined mixture, the sewage itself yields a suffi- ciency of sulphur compounds to produce the sulphuric acid necessary to control the slaking of the lime. The results of the selenitic process on gray chalk lime have been tested by Mr. David Kirkaldy, and his eareful experiments show that the resistance of such lime, whether exposed to a crushing or pulling force, is considerably more than doubled by the selenitic action, though the proportion of sand be twice as much as in the lime used in the ordinary manner. There is every reason to suppose that these results will be surpassed by a hydraulic lime of the same chemical composition as Portland cement, such as can be prepared by the process of which I have en- deavoured to give you an outline. The CHARMAN remarked that he remembered very well that at one of the places where Portland cement was first made in the neighbourhood of London, a very great portion of it was made from the chalk of the district and that which really and truly was the sewage sludge, viz., the deposit of the Thames at Northfleet Creek, Mr. Epmesron asked whether the effluent water by General Scott’s process was available for pur- poses of irrigation or not, and he also wished to know what was the price of the new cement as com- pared either with Portland cement or lime mixed with sand, and also what proportion of sand was needed with the new cement. Mr. BengAmry Ferrey asked what amount of de- posit took place in a sewer over any given length. It was material, if the sludge was to be converted into a building material, to know in what degree it could be made serviceable, because unless there was a large amount of sewage, the process could not be brought into general use. Mr. C. Barry observed that Major-General Scott deserved the warmest thanks of the meeting for the interest with which he had invested the subject. He wished to know what were the proportions of powdered lime and clay that were used in the process, and what amount of deposit was obtained in propor- tion to the quantity of lime and clay used. He should also like to know whether there was any offensive smell driven off during the baking of the deposit. He concluded by proposing a vote of thanks to Major-General Scott for his interesting paper. Mr. Epmeston seconded the motion, and said that the author was deserving of the greatest credit for the persevering way in which he had brought his great scientific knowledge to bear on this matter. Major-General Scott had devoted many years of his life to the elucidation of questions of this kind. From the attention which he (Mr. Edmeston) knew General Scott devoted to such matters, he had every confidence in what that gentleman had brought for- ward, and therefore it would be well for the profes- sion to pay careful attention to the subject. The CHarrMaN, in putting the motion to the meeting, said that the plaster of Paris was used, he presumed, merely as a vehicle for adding sulphuric acid. He quite agreed with what Mr. Edmeston had said with regard to the importance of the sub- ject, for it appeared to him that cne result of this discovery would be a reduction in the price of Port- land cement to the extent of something like 25 or 30 per cent. Major-General Scort, in reply to Mr. Edmeston, saidsuch ardentirrigationists as Mr. Hope would much rather have the effluent water resulting from his pro- cess than the sewage as it was. Dr. Letheby had given similar testimony. It was true that his pro- cess extracted from the liquid a small amount of phosphoric acid, and to that extent the effluent water ‘was injured for purposes of irrigation, but, on the ether hand, the process removed from the liquid all the slime and sludge which on the generality of sewage farms was found to choke the vegetation. As to the price of the new cement, Ealing was too small a town to deal with to enable him tos ay with accuracy what the cost would be. At Ealing they could only produce 5} tons of cement per day. They got a shilling a bushel for it, and there were about thirty bushels to the ton. If a sufficient quantity of plaster of Paris was used, and it was allowed to set selenitically, it would take a large amount of sand. In reply to Mr, Ferrey, he said that the amount of deposit would depend entirely upon the manner in which the sewers were laid. If they were laid with a sufficient fall there would be none. Very frequently they were laid with the fall the wrong way (laughter). In reply to Mr. Barry, he stated that the quantity of increase of deposit obtained depended more upon the nature of the sewage water. This would be more readily intelli- gible by his explaining that some sewage waters contained lime in the condition of sulphate of lime, and in that case his process would not remove it. The sewage water as it came down at Ealing had perhaps thirteen grains of lime per gallon before his process was applied, but after the process it only contained six or seven grains. Taking the average of towns, he got an additional 20 or 30 per cent. of deposit—z.e., in addition to the materials added. There was a slight faint smell, but nothing nearly so bad as the smell which prevailed at ordinary Port- land cement works. If, however, it should ever be found that the smell was disagreeable, it could be carried away in the chimney-shaft. In reference tothe remark made by the chairman, he advised the mem- bers of the profession not to hold out very great ex- pectations of Portland cement, or, in fact, any other building materials, becoming much cheaper. The CHAIRMAN then called upon Mr. R. W. Edis, F.S.A., to read a paper entitled NOTES ON THE RECENT CONFLAGRATIONS IN PARIS. Mr. Epis said that he was in Paris while the fires were still burning, and owing to this and to the confusion and terror prevalent at the time, his notes were necessarily of a fragmentary nature. From such notes as he had been enabled to take, however, he would endeavour to eliminate such portions as he thought would be of special interest to this section of the Conference. In considering this subject in reference to the construction of buildings to resist fire, it should be borne in mind that the fires at Paris were brought about by an exceptionally active incendiarism, and that the most systematic means were employed by the Communists to secure the destruction of the city. Wast quantities of highly combustible materials, such as petroleum and gunpowéer, were called in as auxiliaries in the demoniacal work, to make which the more destruc- tive walls and floors had been knocked through, so as to cause the flames to spread from block to block and from floor to floor. Besides this, it was on record that some buildings had been set on fire in as many as a hundred places, and the destructive work was, no doubt, greatly added to by the falling and bursting of shells among the buildings. The utter uselessness of stone con- struction to resist fire was no new story, and all who knew this would not be surprised to hear of the total failure of the so-called fireproof construction of Paris. The beautiful limestone of which the ex- ternal walls of the buildings were built had been com- pletely licked off, as it were, by the flames, and the subsequent action of damp upon the burnt lime- stone had aided its disintegration, and had caused it to crumble away. Internally, the walls with stone surfaces had been destroyed to so great an extent as to make any restoration short of entire rebuilding impossible. Where, however, the walls had been built of rough stone and plastered over they had suffered little or no damage. As to the effect of fire upon stone staircases and landings, where these were supported solidly, as in the grand staircase of the Tuileries, they had stood fairly well, but in all other cases they had proved useless, and great sources of danger. Ironwork failed lamentably, and by break- ing, snapping, twisting, and turning did more damage than any wood construction could have done. At the immense storehouses at the docks of La Villette the effects of the fire in this respect were terrific. Few cast-iron columns were left stand- ing, but those that were were generally either broken or out of the perpendicular, and the floors had fallen through. As was stated in Captain Shaw’s forthcoming work on fire surveys, in the new build- ings of Paristhe general construction of the walls and the staircases was of stone. The floors were gene- rally of so-called fireproof construction, with rolled or wrought iron joists about 2ft. apart, and filled in with plaster of Paris, or brick or tile blocks. These floors had answered tolerably well, but had mostly failed where heavy débris had fallen upon them and broken holes through them. Many beams of wood of large scantling were found not to be burnt through, and it was generally found that with good plaster-work over them, beams and columns of wood were entirely protected from the fire. In cases where limestone walls had been utterly ruined on the out- side by the flames passing through the window openings, the same walls, internally, escaped almost unscathed, owing to their being coated with plaster. On many such plastered walls the distemper decora- tions were still to be made out. Of the general com- struction of Paris, considered in relation to prevent- ing the spread of fire, he could not speak too highly. Although extraordinary means were taken to secure the spreading of the flames from house to house and block to block, this, with hardly an exceptional case, did not take place. The iron roofs, no doubt, rendered good service in this respect, and the party walls of each house were carried up right through the roof—a most important precaution, for other- wise nothing could have prevented the disastrous conflagration from being more extensive than it was. From the notes he had been able to make he had come to the conclusion that no ironwork, except, perhaps, in roofs, should be employed in buildings intended to resist fire—and all buildings ought to be so constructed—unless well covered with plaster, and that good sound woodwork in beams and posts, good wood floors, well pugged, and good wooden staircases, were safer and more to be depended upon than cast-iron columns and stone staircases, landings, and floors. Stone staircases well protected by plaster were fireproof, although not so safe as wood in case of heavy debris falling upon them. Mr. C. C. Netson proposed a vote of thanks to Mr. Edis for his paper. Captain Suaw, Chief of the Metropolitan Fire Brigade, having been called upon by the Chairman for a few remarks, said that he had very little to add to what Mr. Edis had stated in his paper. He could say, however, that he knew of no instances in which unprotected stone had escaped under the action of fire, and he scarcely knew of one instance of un- protected iron having escaped. He, too, had visited Paris at the same time as Mr. Edis, and he had noticed one point not detailed by Mr. Edis, viz., that hollow iron columns were in all instances destroyed, but the solid columns were, ina very large number of cases, left intact, and in many cases they had only failed owing to the falling of heavy masses of debris upon them, as was the case in oneor two of the theatres. In reply to aquestion by the Chairman, Captain Shaw said he had never had any experience of the effect of fire upon hollow iron columns filled in with Portland cement concrete, but he should think that such columns would stand very well. He could entirely corroborate what Mr. Edis had said as to the inability of the fire to spread from one house to the other. He spent weeks in going over the ruins, but had not traced a single instance of fire extending from one house or block to another except where holes had been blown or knocked in the walls. In reply to a question by a gentleman whose name did not reach the reporters, Captain Shaw said that solid iron stanchions or supports of the com- mon section were much used in the docks and ware- houses of London, and he had known very few in- stances of their failure, and he had scarcely ever seen them bend in the same way as the hollow columns. In reply to Mr. Waterhouse, as to the value of a hollow iron column filled internally with oak, he said that such a column would be a very ex- pensive one tomake, and for his own part he should prefer to use a solid oak column, as in his experience it was a rare thing to see a solid wood column burnt through at all, especially when protected with plaster. The CHarrMAn said he remembered going over the ruins of a factory which was burnt down a few years ago, and whilst he saw that the iron girders and columns were twisted and bent into every imaginable shape by the action of the heat, he noticed that two pieces of wood, which were covered with iron on both sides, were not charred to the depth of an eighth of an inch. Mr. Puene Sriers, who exhibited some excellently- executed water-colour drawings of the ruins of the Tuileries and other buildings destroyed by the fire in Paris, said that French architects unanimously considered that the floors described by Mr. Edis had been of the greatest possible advantage. He had had long conversations on the subject with M. Kestel, M. Duc, and other architects, and it was their opinion that the floors in question had been of great service in keeping the fire within limits. M. Due was of opinion that Londoners were to be con- gratulated on the fact that they had not in their neighbourhood a sufficient quantity of stone to allow of their putting up all their buildings in that material. However, we had brick, and this, wherever it had been tested in Paris, had stood uncommonly well.