ON THE GENERAL DIFFUSION OF KNOWLEDGE. 



cultivated 240 acres of land in La Vendee, on 

 chymical principles, in order to set a good ex 

 ample to the farmers ; and his mode of culture 

 was attended with so much success, that he ob 

 tained a third more of crop than was procured 

 by the us ial method, and in nine years his an 

 nual produce was doubled. 



I might also have illustrated the practical ad 

 vantages of chymical science in relation to the 

 art of extracting metals from their ores, the con 

 version of iron into steel, and the metallic ore 

 into malleable iron the manufacture of glass, 

 alum, copperas, blue vitriol, soda, potash, J\loroc- 

 co-lcather, paper, starch, varnish, and Prussian- 

 blue the refining of sugar, saltpetre, gold and 

 silver the a.rtihcia.\ formation of ice the method 

 of preserving fish, meat, and other articles of 

 food, and various other processes connected 

 with the practical departments of life, all of 

 which arc strictly chymical operations, and can 

 be improved and brought to perfection chiefly 

 by the knowledge and application of the doc 

 trines and facts of chymical science. 



With regard to the professions of the physi 

 cian, surgeon, and apothecary, it is now univer 

 sally admitted, that an extensive acquaintance 

 with the principles and facts of chymistry is es 

 sentially requisite to the successful practice of 

 these arts. The human body may be considered 

 as a species of laboratory, in which the various 

 processes of absorption, secretion, fermenta 

 tion, composition and decomposition are in 

 cessantly going forward. Every article of food 

 and drink we throw into the stomach, every 

 portion of atmospheric air we receive into the 

 lungs, every impression we derive from the sur 

 rounding elements, every motion of the heart 

 and lungs, and every pulse that vibrates within 

 us, may be considered as effecting a chymical 

 change in the vital fluids, and in every part of 

 the animal system ; the nature of which it is of 

 the utmost importance to the medical practi 

 tioner thoroughly to investigate and understand. 

 For, how can he be supposed to be successful 

 in his attempts to counteract the disorders to 

 which the human frame is incident, and to pro 

 duce a chymical effect on the constitution of his 

 patient, if he is ignorant either of the processes 

 which are going on in the system, of the chy-. 

 mical properties of the substances which he 

 throws into it, or of the effects which they will 

 certainly produce ? If he is ignorant of the 

 chymical affinities that subsist between the va 

 rious articles of the Materia Medica, he may 

 often administer preparations which are not 

 only inefficacious, but even poisonous and de 

 structive to his patient. When two chymical 

 substances, each of which might be adminis 

 tered separately with safety, are combined, they 

 sometimes produce a substance which is highly 

 deleterious to the animal system. For example, 

 although mercury and oxygenized muriatic acid 



have both been administered, and either of thero 

 may be taken separately without injury to the 

 animal economy, yet if a medical practitioner, 

 ignorant of the chymical affinities of such sub 

 stances, arid of the quality of the compound^ 

 should give both of them in conjunction, the r.iost 

 dreadful consequences might ensue : since the 

 product of this mixture, oxygenized muriate of 

 mercury, is known to be a most corrosive poi 

 son ; and there can be little doubt that hundreds 

 of lives have been destroyed, by ignorant pre 

 tenders to medical science, in consequence of 

 the injudicious administration of such delete 

 rious preparations. 



But chymistry is not the only science which 

 is of utility in the arts which minister to the 

 comfort and pecuniary interests of society. 

 Geometry, trigonometry, conic sections, and 

 other branches of mathematical knowledge ; hy 

 drostatics, hydraulics, mechanics, optics, bota 

 ny, mineralogy and the other departments of the 

 physical sciences, may be rendered of essential 

 service to artisans and mechanics of various de 

 scriptions. All the sciences are, in some de 

 gree, connected, and reflect a mutual light upon 

 one another; and consequently the man who 

 has the most extensive acquaintance with 

 science, is best qualified for carrying to per 

 fection any one department of the useful arts. 



Practical Geo?netry is highly useful to almost 

 every mechanic and artisan, particularly to 

 mill-wrights, bricklayers, carpenters and ma 

 sons. It teaches them to form angles of any 

 assigned number of degrees, to draw parallel 

 and perpendicular lines, to proportion circumfe 

 rences to diameters, to divide circular rims into 

 any number of parts, to estimate the square or 

 cubical contents of any piece of workmanship, 

 and to calculate the price they ought to receive 

 for any work they perform, according to its 

 solid or superficial dimensions. In forming es 

 timates of the expense of any proposed under 

 taking, the carpenter, bricklayer, and architect 

 must find such knowledge essentially requisite , 

 and even the common labourer who undertakes 

 the formation of roads, the digging of pits, and 

 the clearing away of rubbish, will find the prin 

 ciples of arithmetic and geometry of important 

 service in estimating the rate at which he can 

 perform such operations. The following geome 

 trical theorems, besides many others, are capa 

 ble of a variety of practical applications, in 

 many departments of the arts. &quot; If, from the 

 two ends of any diameter of the circle, two lines 

 be drawn to meet in any one point of the circle 

 whatever, such lines are perpendicular to each 

 other,&quot; or, in other words, they form a right 

 angle at the point of contact.* Again, &quot; The 



* For example, if from the two ends of the diame 

 ter A and B, the lines A C, B C be drawn to the point 

 C, these lines will be perpendicular to each other 

 and consequently the angle at C will be a right an 



