FAMILIAR LETTERS ON CHEMISTRY. 



upon the monopoly lasted. We should probably ere long have triumphed over all 

 difficulties, and have separated it from gypsum. The impulse has been given, the 

 possibility of the process proved, and it may happen in a few years that the incon- 

 siderate financial speculation of Naples may deprive her of that lucrative com- 

 merce. In like manner, Russia, by her prohibitory system, has lost much of her 

 trade in tallow and potash. One country purchases only from absolute necessity 

 from another, which excludes her own productions from her markets. Instead of 

 the tallow and linseed oil of Russia, Great Britain now uses palm oil and cocoa- 

 nut oil of other countries. Precisely analogous is the combination of workmen 

 against their employers, which has led to the construction of many admirable ma- 

 chines for superseding manual labor. In commerce and industry every imprudence 

 carries with it its own punishment ; every oppression immediately and sensibly re- 

 coils upon the head of those from whom it emanates. 



LETTER IV. 



MY DEAR SIR : 



One of the most influential causes of improvement in the social condition of 

 mankind, is that spirit of enterprise which induces men of capital to adopt and 

 carry out suggestions for the improvement of machinery, the creation of new 

 articles of commerce, or the cheaper production of those already in demand ; 

 and we cannot but admire the energy with which such men devote their 

 talents, their time, and their wealth, to realize the benefits of the discoveries and 

 inventions of science. For even when they are expended upon objects wholly 

 incapable of realization nay, even when the idea which first gave the impulse 

 proves in the end to be altogether impracticable or absurd, immediate good to the 

 community generally ensues ; some useful and perhaps unlocked for result flows 

 directly, or springs ultimately, from exertions frustrated in their main design. 

 Thus it is also in the pursuit of science. Theories lead to experiments and 

 investigations ; and he who investigates will scarcely ever fail of being rewarded 

 by discoveries. It may be, indeed, the theory sought to be established is entirely 

 unfounded in nature; but while searching in a right spirit for one thing, the 

 inquirer may be rewarded by finding others far more valuable than those which 

 he sought. 



At the present moment, electro magnetism, as a moving power, is engaging great 

 attention and study: wonders are expected from its application to this purpose. 

 According to the sanguine expectations of many persons, it will shortly be employed 

 to put into motion every kind of machinery, and among other things it will be 

 applied to impel the carriages of railroads, and this at so small a cost, that expense 

 will no longer be matters of consideration. England is to lose her superiority as 

 a manufacturing country, inasmuch as her vast store of coals will no longer avail 

 her as an economical source of motive power. " We," say the German cultivators 

 of this science, " have cheap zinc, and, how small a quantity of this metal is 

 required to turn a lathe, and consequently to give motion to any kind of 

 machinery !" 



Such expectations may be very attractive, and yet they are altogether illusory ! 

 they will not bear the test of many simple calculations ; and this our friends have 

 not troubled themselves to institute. 



With a simple flame of spirits of wine, under a proper vessel containing boiling 

 water, a small carriage of two hundred to three hundred pounds weight can be put 

 into motion, or a weight of eighty to one hundred pounds may be raised to a height 

 of twenty feet. The same effects may be produced by dissolving zinc in dilute sul- 

 phuric acid in a certain apparatus. This is certainly an astonishing and highly 

 interesting discovery ; but the question to be determined is, which of the two 

 processes is the least expensive ? 



In order to answer this question, and to judge correctly of the hopes entertained 

 from this discovery, let me remind you of what chemists denominate "equivalents." 

 These are certain unalterable ratios of effects which are proportionate to each 

 other, and may therefore be expressed in numbers. Thus, if we require eight 

 pounds of oxygen to produce a certain effect, and we 'wish to employ chlorine for 

 the same effect, we must employ neither more nor less than thirty-five and a half 



