A new method of chemistry; including the theory and practice of that art: laid down on mechanical principles ... To which is prefix'd a critical history of chemistry and chemists ... / Translated ... by P. Shaw and E. Chambers with additional notes.

  • Boerhaave, Herman, 1668-1738
Date:
1727
Catalogue details

Licence: Public Domain Mark

Credit: A new method of chemistry; including the theory and practice of that art: laid down on mechanical principles ... To which is prefix'd a critical history of chemistry and chemists ... / Translated ... by P. Shaw and E. Chambers with additional notes. Source: Wellcome Collection.

    10/776 (page 6)
    For chemiftry is no fcience form'd a priori; ’tis no production of the human mind, framed by reafoning and deduction : It took its rife from a number of experiments cafualiy made, without any expectation of what follow’d j and was only reduced into an art or fyftem, by collecting and comparing the effects of fuch unpre¬ meditated experiments, and obferving the uniform tendency there¬ of. So far, then, as a number of experiments agree to eftabliftl any undoubted truth ; fo far they may be confidefd as conftituting the theory of chemiftry. Now, fuch doCtrine or theory is neceffary to • be premifed to every art; and fomething equivalent hereto, is praCtifed by every artizan : To inftruCt his difciples how to proceed orderly to the excrcife of their art, he muft lay them down the general truths or rules thereof. This may bear a little further illuftration : All the experiments ever yet made, agree in this, That no chemical opera¬ tion is perform’d without fluids 5 or that all chemical alteration is effected by means of fome fluid : This, therefore, may be laid down as an univerfal truth, or axiom of chemiftry. Again, from infinite obfervations and experiments, it is found, that there is no fluid without fire $ or that all fluid bodies, as water, oil, fpirits, &c. entirely devoid of fire, become folids: confequent- iy, if there were no fire, all the bodies in nature would fix into one rigid, confident mafs. Whence it eafily follows, that all ope¬ rations are perform’d by means of fire: which is another univerfal truth. Again, from a thoufand experiments, made by as many perfons, in different places, it appears that there is not one grain of fix’d fait in any part of an animal body : So that this, too, may be aflumed as an axiom. From the inftances here brought, it eafily appears, that the truths of chemiftry are none of ’em deduced cl priori, from any abftraCt contemplations of the mind ; but collected a pofieriori, from in¬ numerable experiments. And fuch truths may.be confider’d, either as univerfal phenomena, or canons of chemiftry, or as combinations or fyftems of the particular truths collected, and digefted therein. Now, it were impofiible to teach the practice of chemiftry, to the purpofe, without fome fuch previous theory. To give a novice a parcel of wormwood, for inftance, and bid him diftil, and get the fpirit from it, would be in vain, unlefs he knew before-hand, this general truth, or axiom. That all plants, expofed to a gentle heat.