0 १. conducted to the best advantage only by those who have acquired a knowledge of the chymical changes which take place in these operations. The making of CAST STEEL, which has been kept so profound a secret, is now found to be a simple chymical process, and consists merely in imparting to the metal a portion of carbon, by means of fusing it in crucibles with carbonate of lime. The manufacturers of utensils, &c. in cast iron (called IRON FOUNDERS) will also acquire some valuable information by the study of chymistry; as it will teach them how to mix the different kinds of metals; how to apportion the carbonaceous and calcareous matter; and how to reduce the old metal, which they often receive in exchange; many hundred tons of which are annually sent away as ballast for ships, for want of that knowledge, which would enable them to convert it into good saleable iron. The WOOLLEN, the COTTON, and the CALICO manufactures are also become of great importance to these kingdoms. In order to preserve these sources of national wealth, the utmost attention must be paid to the beauty, the variety, and the durability of their several colours. Now of all the arts, none are more dependent upon Chymistry than those of DYING and CALICO FRINTING. Every process is chymical; and not a colour can be imparted, but in consequence of the affinity which subsists between the cloth and the dye, or the dye and the mordant which is employed as a bond of union between them. It is surely then evident how valuable a chymical education must be to that youth who is designed for either of these trades, and how necessary is that portion of knowledge which shall enable him in a scientific manner to analyse his different materials, and to determine the kind and the quantity necessary for each process. After all, his colours will be liable to vary, if he do not take into the account, and calculate upon, the changes which take place in them by the absorption of oxygen. A knowledge of which, and of the different degrees of oxidizement, which the several dyes undergo, requires no small share of chymical skill; and yet this skill is absolutely necessary, to enable either the dyer or the calico printer to produce in all cases permanent colours of the shade which he intends. Moreover, these artists must be indebted to chymistry for any valuable knowledge which they may acquire of the nature of the articles they use in their several processes; not to say that they are wholly dependent upon this science, for the artificial production of their most valuable mordants, and for some of their most beautiful and brilliant colours. The art of BLEACHING, which is so intimately connected with calico printing, has also received such great improvement from the science of chymistry, that no man is now capable of conducting it possession of the knowledge which he may now acquire by a cultivation of chymical science. And, though the operation of many of the poisons upon the system be in these days well understood, nothing but a knowledge of chymistry can enable the practitioner to administer such medicines as will counteract their baneful effects*. If we look to the MANUFACTURES of the kingdom, there is scarcely one of any consequence, that does not depend upon chymistry, for its establishment, its improvement, or for its successful and beneficial practice. In order to see the connexion which sub. sists between chymistry and the arts, it will be necessary to take a short view of the principal trades which are carried on in these. kingdoms. One of the staple trades of the country is the manufacture of iron; and it will be found, that from the smelting of the ore to the conversion of it into steel, every operation is the effect of chymical affinities. In the first place, it requires no small share of chymical knowledge to be able to appreciate the value of the different ores, or to erect furnaces for their reduction, which shall be contrived in the best possible manner for facilitating their fusion, and for producing good pigs. The subsequent process to convert it into malleable iron, are entirely chymical, and will be *The following fact will show the importance of chymical knowledge to every practitioner in medicine more forcibly than a thousand arguments. Having myself been instrumental in saving a valuable life, I feel great pleasure in relating the circumstance. About christmas last an apothecary, in one of the northern counties, having drunk some bettled porter, was seized with symptoms which convinced him that he was poisoned; but not knowing what noxious matter he had taken, and being incapable of analysing the remainder, no antidote could be applied, and he gave himself up as lost. A physician had been called in, but neither he, nor the patient, nor his partner, could get any information by examining the remaining contents of the fatal bottle, though, I understand, they are all intelligent men, and in great reputation in their profession. In this dilemma what could be done? At last one of them recollected that a neighbouring gentleman had the reputation of being a good chymist. To him the physician and the partner of the patient hastened, to get the dregs a:.alysed, and to learn what ought to be administered. Fortunately, this gentleman had just received Gottling's Book of Tests, which I had procured for his brother, and which had been sent to him but a very short time before. By this book he was enabled to ascertain that the poison was oxide of antimony: and when the patient was informed of it, he recollected that antimonial wine had been kept in the bottle some years before; and supposed that the porter must have been bottled without the dregs being properly washed out. When the nature of the poison was thus ascertained, the gentleman had no difficulty in directing the physician to a proper antidote, which was administered immediately; and the life of the unfortunate man was preserved; but, in consequence of the time allowed to elapse previous to its exhibition, the poison had so far taken possession of the system as to deprive him of the use of a limb, conducted to the best advantage only by those who have acquired a knowledge of the chymical changes which take place in these operations. The making of CAST STEEL, which has been kept so profound a secret, is now found to be a simple chymical process, and consists merely in imparting to the metal a portion of carbon, by means of fusing it in crucibles with carbonate of lime. The manufacturers of utensils, &c. in cast iron (called IRON FOUNDERS) will also acquire some valuable information by the study of chymistry; as it will teach them how to mix the different kinds of metals; how to apportion the carbonaceous and calcareous matter; and how to reduce the old metal, which they often receive in exchange; many hundred tons of which are annually sent away as ballast for ships, for want of that knowledge, which would enable them to convert it into good saleable iron. The WOOLLEN, the COTTON, and the CALICO manufactures are also become of great importance to these kingdoms. In order to preserve these sources of national wealth, the utmost attention must be paid to the beauty, the variety, and the durability of their several colours. Now of all the arts, none are more dependent upon Chymistry than those of DYING and CALICO FRINTING. Every process is chymical; and not a colour can be imparted, but in consequence of the affinity which subsists between the cloth and the dye, or the dye and the mordant which is employed as a bond of union between them. It is surely then evident how valuable a chymical education must be to that youth who is designed for either of these trades, and how necessary is that portion of knowledge which shall enable him in a scientific manner to analyse his different materials, and to determine the kind and the quantity necessary for each process. After all, his colours will be liable to vary, if he do not take into the account, and calculate upon, the changes which take place in them by the absorption of oxygen. A knowledge of which, and of the different degrees of oxidizement, which the several dyes undergo, requires no small share of chymical skill; and yet this skill is absolutely necessary, to enable either the dyer or the calico printer to produce in all cases permanent colours of the shade which he intends. Moreover, these artists must be indebted to chymistry for any valuable knowledge which they may acquire of the nature of the articles they use in their several processes; not to say that they are wholly dependent upon this science, for the artificial production of their most valuable mordants, and for some of their most beautiful and brilliant colours. The art of BLEACHING, which is so intimately connected with calico printing, has also received such great improvement from the science of chymistry, that no man is now capable of conducting it to the best advantage without a knowledge of the principles on which the present practice is established. The manufactures of EARTHEN WARE and PORCELAIN, which were so much improved and extended by the industrious and ingenious Wedgewood, and which are become by his means a source of national wealth, and give employment to thousands of the community, are dependent upon chymistry for the successful management of all their branches, from the mixture of the materials which form the body of the ware, to the production of those brilliant colours which give a value to the manufactures by their permanency and beauty. Mr. Wedgewood was so sensible of the importance of chymistry to these arts, that he not only applied to the study of the science himself, but upon the death of the celebrated Dr. Lewis (author of the Commercium Philosophico-Technicum) he actually engaged his assistant, a Mr. Chisolme, to experimentalize with him, and to devote his whole time to the improvement of the manufac ture by the application of his chymical knowledge, of which perhaps few men in the kingdom at that time had a larger share. A faint idea of the advantages which he derived from these sources may be conceived from the following circumstance. Dr. Bancroft in his Philosophy of permanent colours, when treating on iron, says, "I remember having been told, by Mr. Wedgewood, that nearly all the fine diversified colours applied to his pottery were produced only by the oxides of this single metal." This one fact is sufficient to show with what assiduous application he must have studied chymical science, and how insufficient every attempt to bring his manufacture to the perfection which it has now attained, would have been, without this attention. The sister art of making GLASS is also entirely chymical, consisting in the fusion of siliceous earth with the oxides of lead and alkali. In this trade, as well as in many others, the chymical manufacturer, and the man of enlightened experience, will have many advantages. He will not only know how to analyse his alkalies and to ascertain their exact value before he purchases, but he will be enabled, on chymical principles, to ascertain the exact quantity necessary for any fixed portion of silex, which with others must always in the first instances be a matter of uncertainty, and must repeatedly subject them to losses and disappointment. The TANNING OF HIDES is a process which was formerly carried on by persons who merely followed a routine of operations to which they had been accustomed without knowing the real cause of any of the changes produced on these substances. This art, which consists in impregnating the animal matter with a peculiar principle taken from the vegetable kingdom, which enables it to resist moisture, and gives it great strength and firmness, has been well explained by Mr. Seguin. According to him, the gallic acid of the bark deoxidizes the skin, and as the skin loses its oxygen the tan combines with it, and forms it into leather*. It is now known, that many substances, besides oak bark, contain tan, and to modern chymistry we are indebted for the means of discovering with accuracy the quantity of tan which the several astringent vegetables contain. The arts will owe a further obligation to this science whenever it shall lead the way to the discovery of a cheap substitute for oak bark. At present the demand is so great that it is not only imported from the continent, but trees are cut down in this country on purpose for the bark, which are of no other use whatever. Should the chymical tanner not be fortunate enough to make a discovery of the kind just mentioned, he will at least be able to analyse the substances now in use, and to appreciate their relative value; a matter of no small moment to a man who operates upon a large scalet. The manufacture of SOAP, a trade of considerable importance, and which materially aids the revenue of the country, has in general been conducted, like many of the foregoing, without any regard to system; and yet, perhaps, there is no art which may be benefitted in such various ways by chymistry as this. To those who are designed for this trade I have no hesitation in recommending the study of the science as a matter of the first importance. Many thousands per annum, which are now lost to the community, would be saved, if the trade was in general carried on upon scientifick principles. Make a soap boiler a good chymist and you teach him how to analyse barilla, kelp, potash, &c. so as to ascertain the proportion of alkali in each, and which is the most advantageous for him to purchase; a matter of mere guess with the common manufacturer. When these articles are at an exorbitant price, he will have recourse to various residuums, which he will decompose by chymical means, and make use of as substitutes. He will learn, in choosing his tallows, how to avoid those which contain a large portion of sebacic acid, which require much more barilla than good tallow, and yet produce less soap. He will know how to oxidize the common oils and oil dregs, so as to give them consistence, and render them good substitutes for tallow. He will know how to apportion his lime so as to make his alkali perfectly caustic, without using an unnecessary quantity of that article. He *See his "Report to the Committee of Public Safety, on the new Methods of Tanning." It is printed in Annales de Chimie, tom. 20, 15. See also Mr. Davy's Paper on this subject, in the Philos. Trans. vol. 93, 233. + Davy. |