vi Preface 



was not possible to obtain a clear idea of Mayow's 

 scientific position without reading the whole of the 

 five treatises. We therefore now present to the 

 reader a translation of Mayow's Opera omnia. Our 

 rule has been to translate as literally as possible, 

 avoiding the use of any words or phrases which have, 

 since Mayow's time, acquired a special scientific 

 meaning. This has led to the retention of expres- 

 sions not now familiar to scientific readers. Some of 

 these we may here note. Sulphur is often used for 

 what may be called the combustible principle, and 

 sulphureous matter almost always means combustible 

 matter, without any suggestion that it contains 

 sulphur in the sense we should mean if we used the 

 phrase now. There is no difficulty in seeing quite 

 clearly when Mayow uses the word sulphur in the 

 general and when in the special sense. 



By *' purely saline salt" he means an alkali, fixed or 

 volatile, usually a carbonate ; and " fixed salt " means 

 potash or soda, usually as carbonate. It is scarcely 

 necessary to say that the nature of the difference 

 between the caustic and the mild alkalis was not 

 discovered till nearly a hundred years after Mayow's 

 time. 



We have confined ourselves to the work of transla- 

 tion and have added nothing in the way of commen- 

 tary or criticism ; but it may be well to remind the 

 reader that Hooke's Micrographia had been published 

 shortly before Mayow wrote, and that most of Boyle's 

 treatises appeared shortly after. 



The edition of Mayow's works printed at Oxford 

 in 1674 has been used in the preparation of the 

 translation. 



A. C. B. 

 L. D. 



