Experiments and Observations on Different Kinds of Air. Joseph Priestley

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СКАЧАТЬ id="ulink_d450646d-6919-5813-931e-7ef2474b055a">There certainly never was any period in which natural knowledge made such a progress as it has done of late years, and especially in this country; and they who affect to speak with supercilious contempt of the publications of the present age in general, or of the Royal Society in particular, are only those who are themselves engaged in the most trifling of all literary pursuits, who are unacquainted with all real science, and are ignorant of the progress and present state of it.[1]

      It is true that the rich and the great in this country give less attention to these subjects than, I believe, they were ever known to do, since the time of Lord Bacon, and much less than men of rank and fortune in other countries give to them. But with us this loss is made up by men of leisure, spirit, and ingenuity, in the middle ranks of life, which is a circumstance that promises better for the continuance of this progress in useful knowledge than any noble or royal patronage. With us, politics chiefly engage the attention of those who stand foremost in the community, which, indeed, arises from the freedom and peculiar excellence of our constitution, without which even the spirit of men of letters in general, and of philosophers in particular, who never directly interfere in matters of government, would languish.

      It is rather to be regretted, however, that, in such a number of nobility and gentry, so very few should have any taste for scientifical pursuits, because, for many valuable purposes of science, wealth gives a decisive advantage. If extensive and lasting fame be at all an object, literary, and especially scientifical pursuits, are preferable to political ones in a variety of respects. The former are as much more favourable for the display of the human faculties than the latter, as the system of nature is superior to any political system upon earth.

      If extensive usefulness be the object, science has the same advantage over politics. The greatest success in the latter seldom extends farther than one particular country, and one particular age; whereas a successful pursuit of science makes a man the benefactor of all mankind, and of every age. How trifling is the fame of any statesman that this country has ever produced to that of Lord Bacon, of Newton, or of Boyle; and how much greater are our obligations to such men as these, than to any other in the whole Biographia Britannica; and every country, in which science has flourished, can furnish instances for similar observations.

      Here my reader will thank me, and the writer will, I hope, forgive me, if I quote a passage from the postscript of a letter which I happen to have just received from that excellent, and in my opinion, not too enthusiastical philosopher, father Beccaria of Turin.

      Mi spiace che il mondo politico ch'è pur tanto passeggero, rubbi il grande Franklin al mondo della natura, che non sa ne cambiare, ne mancare. In English. "I am sorry that the political world, which is so very transitory, should take the great Franklin from the world of nature, which can never change, or fail."

      I own it is with peculiar pleasure that I quote this passage, respecting this truly great man, at a time when some of the infatuated politicians of this country are vainly thinking to build their wretched and destructive projects, on the ruins of his established reputation; a reputation as extensive as the spread of science itself, and of which it is saying very little indeed, to pronounce that it will last and flourish when the names of all his enemies shall be forgotten.

      I think it proper, upon this occasion, to inform my friends, and the public, that I have, for the present, suspended my design of writing the history and present state of all the branches of experimental philosophy. This has arisen not from any dislike of the undertaking, but, in truth, because I see no prospect of being reasonably indemnified for so much labour and expence, notwithstanding the specimens I have already given of that work (in the history of electricity, and of the discoveries relating to vision, light, and colours) have met with a much more favourable reception from the best judges both at home and abroad, than I expected. Immortality, if I should have any view to it, is not the proper price of such works as these.

      I propose, however, having given so much attention to the subject of air, to write, at my leisure, the history and present state of discoveries relating to it; in which case I shall, as a part of it, reprint this work, with such improvements as shall have occurred to me at that time; and I give this notice of it, that no person who intends to purchase it may have reason (being thus apprised of my intention) to complain of buying the same thing twice. If any person chuse it, he may save his five or six shillings for the present, and wait five or six years longer (if I should live so long) for the opportunity of buying the same thing, probably much enlarged, and at the same time a complete account of all that has been done by others relating to this subject.

      Though for the plain, and I hope satisfactory reason above mentioned, I shall probably write no other histories of this kind, I shall, as opportunity serves, endeavour to provide materials for such histories, by continuing my experiments, keeping my eyes open to such new appearances as may present themselves, investigating them as far as I shall be able, and never failing to communicate to the public, by some channel or other, the result of my observations.

      In the publication of this work I have thought that it would be agreeable to my readers to preserve, in some measure, the order of history, and therefore I have not thrown together all that I have observed with respect to each kind of air, but have divided the work into two parts; the former containing what was published before, in the Philosophical Transactions, with such observations and corrections as subsequent experience has suggested to me; and I have reserved for the latter part of the work an account of the experiments which I have made since that publication, and after a pretty long interruption in my philosophical pursuits, in the course of the last summer. Besides I am sensible that in the latter part of this work a different arrangement of the subjects will be more convenient, for their mutual illustration.

      Some persons object to the term air, as applied to acid, alkaline, and even nitrous air; but it is certainly very convenient to have a common term by which to denote things which have so many common properties, and those so very striking; all of them agreeing with the air in which we breathe, and with fixed air, in elasticity, and transparency, and in being alike affected by heat or cold; so that to the eye they appear to have no difference at all. With much more reason, as it appears to me, might a person object to the common term metal, as applied to things so very different from one another as gold, quicksilver, and lead.

      Besides, acid and alkaline air do not differ from common air (in any respect that can countenance an objection to their having a common appellation) except in such properties as are common to it with fixed air, though in a different degree; viz. that of being imbibed by water. But, indeed, all kinds of air, common air itself not excepted, are capable of being imbibed by water in some degree.

      Some may think the terms acid and alkaline vapour more proper than acid and alkaline air. But the term vapour having always been applied to elastic matters capable of being condensed in the temperature of the atmosphere, especially the vapour of water, it seems harsh to apply it to any elastic substance, which at the same time that it is as transparent as the air we breathe, is no more affected by cold than it is.

      As my former papers were immediately translated into several foreign languages, I may presume that this treatise, having a better title to it, will be translated also; and, upon this presumption, I cannot help expressing a wish, that it may be done by persons who have a competent knowledge of subject, as well as of the English language. The mistakes made by some foreigners, have induced me to give this caution.

      London, Feb.

       1774.

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