1855.] 



ON HYDRAULIC LIMES, ARTIFICIAL STONES, &c. 



333 



were two — the one was, in contviving a self-acting apparatus 

 for feeding the cylinder with the requisite fluid, at such a 

 constant ;md controllable degree as experience has found suit- 

 able in the printing with flat blocks by manual labour; the 

 other was in the discovery of some new means to dispense 

 with the bathing of the printed stuft' either in a mordant or in 

 a colouring bath, whenever paper is the stufi' to be printed on; 

 as unsized paper, which is the most suitable for the purpose, 

 will not boar, in a wet state, being drawn through the machine. 

 Besides, it was desirable that the diflcrent successive operations 

 which are performed in printing textile manufactures should 

 be done at one time and in a single revolution of the machine, 

 in order to reduce the cost of manufacture to its minimum. 



I have made the cylinder-feeding apparatus in the shape of 

 a trough, in which the wetting fluid is kept at a constant level 

 through a reservoir from above' and a discharge from below. 

 A cloth, one side of ..which is immersed in the liquid, acts by 

 capillary attraction as a syphon, and coinmunicates the liquid 

 in a continuous supply to to the revolving cylinder with which 

 it is in contact from the other side — an elastic cushion placed 

 between the trough and the cloth securing the requisite 

 equality of pressure of the latter upon the cylinder, while a 

 pair of screws pressing on the back of the trough serve to 

 regulate at will the degree of such pressure. This apparatus 

 answers the purpose perfectly well. 



In order to dispense with the bathing of the printed' stuff, I 

 had recourse to the metallic sulphurets, which are known to 

 produce more lasting colours than the vegetable dyeing stufis. 

 Therefore I contrived to obtain the required effects by using 

 for the printing menstrum any of those metallic salts, such as 

 copper, iron, &o., which by the action of hydrosulphuretted 

 acid or alkalies are precipitated in the state of metallic coloured 

 sulphurets ; I use such reagents in the gaseous form, such as 

 hydrosulphuretted ammoniacal gas. The printed stuiF is 

 made to pass direct from the cylinder after it is printed, through 

 a box, which is kept constantly supplied with a current of gas; 

 it comes out of the box completely finished; then, passing 

 through a stove kept at a moderate heat, dries — and lastly 

 winds itself round a reel, ready for sale. In this way the 

 thorough printing of the stufl' in a single revolution of the 

 nuichine is performed. 



The principle of using the hydrosulphurets in the gaseous 

 state in the art of dyeing, which, as far as my knowledge goes, 

 has never been done before, is of considerable importance in 

 that branch of manufacture, as it produces the most satisfac- 

 tory re.sults with the greatest convenience and cheapness, while 

 it entirely obviates the evil arising from the noxious evapo- 

 rations of the hydrosulphurets when used in the liquid state 

 and left to evaporate in the open air. 



On Hydraulic Limes, 



ARTIFICIAL STONES, AND DIFFERENT NOVEL APPLICATIONS 

 OF SOLUBLE ALKALINE SILICATES. 



IIV M. lit. KUULMAN.* 



Entrusted, about the close of the year 1840, with some trials 

 relative to sonic abundant efflorescence, wliich was formed on 

 a perfectly new building, and which was considered to be due 

 to the formation of nitre, 1 was soon convinced that the efllo- 

 rescent salts were formed to a great extent of carbonate of soda, 

 and that the lime which bad been used (hydraulic lime, from 



* Cosmos. 



the neighbourhood of Tournay), was the cause of the efflores- 

 cence which had been observed. A closer examination soon 

 taught me that all limes, and particularly h\-draulic limes and 

 natural cements, contained appreciable quantities of pota.sh and 

 soda. 



TIIEOIIY OF UVDRAULIC LIMES. 



In a work which I had the honour of presenting to the Aca- 

 demy, at a meeting held on the 5th of 3Iay, 1841, I endea- 

 voured to explain the part which potash and soda iftight play 

 in stones and cements, and I admitted that these alkalies served 

 to bring the silica to the lime, and thus to form silicates, which, 

 by means of the application of water, solidified a portion of the 

 mass, producing the formation of a hydrate, analagous to that 

 which takes place with plaster. I have pointed out since then 

 to the Academy numerous facts as the basis of this theory, and 

 that, among others, of the immediate change from fat lime to 

 hydraulic lime, by simply treating with a solution of silicate of 

 potash. If, after the burning of the limestone, potash is in 

 contact with silica, the silicate which is formed must neces- 

 sarily react, and this can only take place as soon as the burnt 

 lime is brought into coutact with water. 



I have greatly added to my experiments on this head, and I 

 have established the fact that, with fat lime and silicate of pot- 

 ash, both of them pulverised and mixed in the proportion of 

 10 or 12 of silicate to 100 of lime, a lime can be obtained which 

 shall have all the characteristics of hydraulic lime. If these 

 substances are not well pulverised the reaction will be very in- 

 complete, and an elfect will subsequently be produced, bring- 

 ing on disintegration. If from my former trials there results 

 the possibility of converting a fat lime into an hydraulic mortar, 

 by sprinkling it with a solution of an alkaline silicate, in my 

 more recent trials I have found a means of producing at once 

 with a vitreous silicate and lime, hydraulic cements of any re- 

 C[uired degree of strength. This will enable us to form, at a 

 reasonable expense, buildings to stand the action of water, in 

 places where fat limes alone are now found. Powdered silicate 

 of potash in some sort becomes an agent for producing this 

 hydraulic property, of which future experience will determine 

 the value. 



ARTIFICIAL STOKES. 



Looking at the great affinity of lime for silica dissolved in 

 potash, I was naturally led to examine the acjtion of alkaline 

 silicates on calcareous stones. Here I was still more fortunate, 

 for the alkaline silicates became at once the means of a variety 

 of applications of the highest utility. Let us look at what is 

 said on this point in the Cumjifts Jiciidiis of the Society's 

 meetings. 



"13y mixing some powdered chalk in a solution of silicate of 

 potash, a cement is obtained, which hardens slowly in the air, 

 assuming a degree of stiffness, which, under certain circum- 

 stances, I'endcis it applicable for the restoration of public mon- 

 uments and the manufacture of moulded articles. 



" Chalk, whether in an artificial paste or in its natural st^ite, 

 plunged into a solution of silicate of potash, takes up, even 

 when cold, a quantity of silica, which may be increased consi- 

 derably bj' exposing the chalk alternately to the action of flie 

 siliceous solution and the air. The chalk assumes a smooth 

 appearance, a compact grain, and a colour more or less yellow, 

 according as it is more or less impregnated with iron. 



"Stone thus prepared is susceptible of a high polish. The 

 hardness, which is at first but superficial, penctr.itcs by degrees 

 into the centre, even where there is considerable thickness. It 

 appears capable of becoming of iiicontestible utility in the form- 



