on the Cahmation of Metals. 79 



Essays by John Rey, Doctor of Physic, on an Inquiry into the 

 Cause ivhy Tin and Lead increase in Weight by Calcination*. 



Preface. 

 Some illustrious persons, having remarked with admiration, 

 that tin and lead increase in weight, when we calcine them, 

 conceived a laudable desire to ascertain the cause. The sub- 

 ject was fine, the inquiry painful, the fruit small ; for, having 

 turned their thoughts on all sides, they adduced such weak 

 reasons for it, that no man of good judgment could venture to 

 rely on them, nor feel his mind thereby relieved of its doubt. 

 M. Brun, an apothecary at Bergerac, having lately observed 

 this increase, and thinking, as I believe, that no one had 

 noticed it before him, requested me, by letter, to turn the 

 subject in my mind, and furnish him with the cause of it. 

 Now, because he is a person whom the integrity of his life, his 

 rare experience in his art, and other virtues, compel all worthy 

 men to wish well to, I avow, they have had such power over 

 my affections, that I could not deny his request. At hi ; 

 prayers and amiable solicitation^, therefore, I have devoted 

 some hours to the subject, and thinking that I have hit the 

 mark, I publish these, my Essays, respecting it. Not, however, 

 without very well foreseeing that I shall incur the imputation 

 of rashness, since I hereby encounter opinions, for ages ap- 

 proved of by most philosophers. But what rashness can there 

 be, in bringing truth, when known, to light? Might I not 

 more justly be deemed puerilely timid, if I dared not divulge 

 it, or sordidly envious, if I kept it concealed ? I protest against 

 these two last censures, hoping also to be acquitted of the first, 

 by all liberal minds, who, having tasted my reasons, if they 

 find them palatable, will thank me for having brought them 



* The increased weight of these metals by calcination has been ob- 

 served from the beginning of chemistry. Geber, de Satvrno, says of lead, 

 " non conservat jirojn'ium pondus in travsntu/adone, sed in norum pondits 

 mutntur, el hoc totum magisterio ncquirit" Tha same author says also, of 

 tin, " *l pondus acquiril in magisterio hitjus arlii." 



t Literal. 



