1850.] 



THK CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



2i\ 



at a heat below tliat required to bring the metal to the fluid state. 

 The metallic product obtained in this way, when operating upon a 

 manufacturing scale, can never be obtained absolutely free from 

 the last portions of earthy or other impurity, and always contains 

 some portion of oxide of iron, which renders it quite unfit for con- 

 version into steel of good quality, as it comes from the process of 

 deoxidation without further treatment. 



To make a perfect steel iron, the metallic product is taken as it 

 comes from the process of cementation or deoxidation, and mixed 

 with a small portion of oxide, or chloride of manganese, and a cer- 

 tain portion of coal or fir tar, or any cheap hydrocarbon or carbon- 

 aceous matter. The best results are obtained from the mixture of 

 from one to three pounds of oxide or cliloride of manganese, and 

 from one to two gallons of coal or other tar to each one hundred 

 pounds of deoxidated ore. The mixture of granular iron tar and 

 manganese, resulting from this process, is heated in a suitable 

 furnace; and when the iron is at a welding heat it is removed 

 from the furnace, and subjected to the action of some suitable 

 instrument of compression, in order to be formed into a solid bloom 

 by any of the usual processes now in use. The bloom is tlien to 

 be reheated and shingled, hammered, or rolled into bars in the 

 usual manner. The bar-iron so produced is to be converted into 

 steel by the well-known processes now in use, and its quality will 

 be found superior to that made from the best iron hitherto 

 procurable. 



VITRIFIED BRICKS. 



^ViLLTAM Gilbert Elliott, of Blisworth, Northampton, gen- 

 tleman, for '■^improvements in the manufacture of brides, tiles, and 

 pipes, and other articles from plastic materials. (A communica- 

 tion.)— Granted April 27; Enrolled May 27, 1850. 



This invention relates to manufacturing bricks, tiles, pipes, and 

 other articles, from clay, melted or fused, and run into moulds of 

 the shape of the articles required to he produced. The clay, as it 

 is dug from the pit, if dry, is conveyed to an air or blast furnace, 

 wherein it is brought to a state of fusion, and then run into the 

 moulds, %vhich should be as close to the furnace as possible; for 

 the melted clay should be introduced into the moulds at a high 

 degree of heat; as it will not hear to be conveyed in ladles or run 

 through trougbs into the moulds. The moulds may be made of 

 iron or other suitable material. The moulds may be carried to 

 and from the furnace by an endless wire web or band, which 

 moves beneath the furnace, and thus brings the moulds close 

 to the opening from which the fused clay is discharged. 



GLAZING CAST-IRON. 



William Wyatt, of Waterloo Cottage, Oldswinford, Worcester, 

 pump-maker, for ^^improvements in coating the surfaces of pumps, 

 pipes, cisterns, and other articles of iron," — Granted October 18, 

 1849; Enrolled April 18, 1850. 



The improvement relates to coating cast-iron pumps, cast-iron 

 pipes, cast-iron cisterns, and other articles of cast-iron, w ith a glass 

 or glaze composed of lead, borax, and silex, combined in the propor- 

 tion of three parts, by weight, of white lead (of one of red lead 

 and two of white lead), two parts of borax, and one part of cal- 

 cined flint, well mixed together and fused in a crucible, then run 

 into water, and ground with water in a glaze-mill. AVhen the 

 mixture is thoroughly reduced, so that it will readily pass through 

 a silk or lawn sieve, such as are used by china manufacturers, it 

 will be ready for use: it is not absolutely necessary to fuse the 

 materials, but it is better to do so. The glaze thus prepared being 

 about the consistence of cream, is applied to the inner surfaces of 

 the pump-barrels, pipes, and similar articles of cast-iron, by 

 closing one end, introducing a quantity of glaze, turning the 

 article round, so as to coat the interior uniformly with the glaze, 

 and then pouring out the surplus. The interior of cisterns and 

 like articles of cast iron is coated in a similar manner, by intro- 

 ducing a quantity of glaze and moving the article about in'various 

 directions until the interior is uniformly coated. In general it 

 will only be necessary to scour and wash the surface previous to 

 coating; but if the surface is much oxidised, it is requisite to 

 subject the articles to a red heat, and, when cool, to scour them 

 well with water. It is preferred to warm the metal before the 

 application of the glaze, in order to facilitate the drying of the 

 latter. The exterior surfaces of articles of cast-iron may be coated 



by dipping the articles into the semi-fluid glaze, or by applying 

 the glaze thereto with a brush. 



After the pumps, pipes, cisterns, or other articles of cast-iron 

 have received a coating of glaze, they are to be subjected to a 

 suitable temperature for firing the glaze and thereby causing it to 

 adhere. This is effected by placing the articles in a kiln heated 

 in such manner that no flame or sulphur shall come in contact 

 with the articles. The heat is gradually raised until the glaze 

 melts (which can be seen by taking out a brick from an opening in 

 the kiln); and, so soon as the melting of the glaze takes place, the 

 fires are drawn, and the articles are allowed to cool: when tlie 

 articles have become cool, they are removed from the kiln, and are 

 ready for use. 



REVIE'WS. 



Practical Ventilation, as applied to Public, Domestic, and Agricultural 

 Structures. By Robkrt Scott Burn, Engineer. Blackwood and 

 Sons, Edinburgh and London. 1850. 



The importance of ventilation in connection with sanitary pro- 

 gress is an admitted fact, that does not require us now to descant 

 upon. What has to be considered is, how ventilation may be 

 applied to buildings effectively and economically: it is to these 

 considerations that the author has devoted his attention. Mr. 

 Burn first points out the necessity and importance of ventilation; 

 and next shows how it may be applied to public buildings, and 

 observes, that 



"Natural ventilation does not depend upon machinery for its 

 results, but is 'a process by which movements are induced or sus- 

 tained in the aii;, in tlie same manner as wind is produced in the 

 external atmosphere.' The rationale of natural ventilation cannot 

 be better described than in the words of Dr. Reid: 'The specific 

 gravity of air vitiated by respiration and combustion, the tv/o 

 great processes that deteriorate air in ordinary buildings, is under 

 ordinary circumstances less than that of common air: it gives 

 way accordingly, and is pressed upwards by the denser and purer 

 air. Let us imagine, then, an apartment occupied by a number of 

 persons standing on a porous floor, and the roof taken off; r.t 

 ordinary temperatures, the air, vitiated there by tlie human frame, 

 requires no mechanical power to remove it. 'i'he superincumbent 

 pressure is diminished by the expansion induced in the air as it is 

 heated; but the external air is permitted to have free access 

 below, as well as above, to the porous floor. Its power therefore 

 preponderates, and an upward movement is the necessary conse- 

 quence; %vhich is accompanied by the introduction of fresh air .ind 

 the removal of that which is vitiated. Here, then, is a species of 

 natural ventilation. All that is essential is merely this, thnt the 

 natural movements induced by the heat of the body shall not be 

 stopped by any barrier opposed to them. An open roof and ceiling 

 is, however, inadmissible: protection is required from the weather, 

 independent of other arrangements. The opening, accordingly, 

 may be contracted: in proportion to the amount of contraction, 

 the temperature of the air, and tlie numbers on a given space, it 

 now becomes necessary to increase the velocity of the discharge 

 from the apartment referred to. To effect this, if a shaft or 

 chimney be extended from any opening in or near the ceiling, the 

 column of warm air which soon fills it increases its power; and 

 unless an extreme number of individuals be crowded in the apart- 

 ments, the shaft is sufficient fur all ordinarij purposes' 



"In ventilating buildings, two tilings should be borne in mind; 

 and as upon the proper attention to these depends the success ol 

 the plan, particular attention should be taken to see them carried 

 into effect. These are, the supply of tiie interior with fresh air, 

 and the withdi-awing of it when vitiated. And here we would 

 request attention to the fact, of which the evidence of all experi- 

 ence goes to prove the truth — that no foul air can by any possibilitjf 

 be extracted from the interior of any building, however vwll arrangeH 

 the means to insure its exit may lie, unless an ample supply of pure air 

 is admitted. In making provisions for the supply of pure air, due 

 regard should be had to the source from which it is supplied. If 

 much dust or extraneous mechanical impurities should be at the 

 base of the building, or drains near to or passing through there, tiie 



air should be led from a distance from the ground And in order 



to stop the ingress of all extraneous particles of dust, Sec. througli 

 the ventilator, there should be stretched across the inside of 

 the opening, sheets of very finely perforated zinc or horse-hair 

 cloth. Where the air has to be led into the interior of a church, 

 say to the passages, ventiducts must be employed to conduct the 



