PREFACE. XIX 



the events to which it relates, Newton appears to have made 

 one or two mistakes of date, and probably for this reason has 

 drawn his pen through the entire passage. 



Newton's manuscripts on Alchemy are of very little interest 

 in themselves. He seems to have made transcripts from a 

 variety of authors, and, if we may judge by the number of 

 praxes of their contents which he began and left unfinished, he 

 seems to have striven in vain to trace a connected system in 

 the processes described. He has left, however, notes of a 

 number of his own chemical experiments made at various 

 dates between 1678 and 1696. Some of these are quantitative. 

 Those of most interest relate to alloys. He mentions several 

 easily fusible alloys of bismuth, tin and lead, and gives as the 

 most fusible that which contains 5 parts of lead + 7 of tin + 12 

 of bismuth. He says that an alloy consisting of 2 parts of 

 lead + 3 of tin + 4 of bismuth will melt in the sun in summer. 

 The alloy which goes by his name is not in the proportions of 

 either of these two ; but, as he states that tinglas (bismuth) is 

 more fusible than tin, he could not have used pure metal. 



The note-book which contains the longest record of his 

 chemical experiments contains also the account of a few optical 

 and other physical experiments and the paper on the decussa- 

 tion of the optic nerve published by Harris and from him by 

 Brewster. Harris, according to Brewster, published from a 

 copy in the Macclesfield Collection; but the copy seems to have 

 been identical with that in this book, except that a paragraph 

 at the end is omitted. Brewster overlooked the paper in this 

 book, though he has quoted from other parts of the book. 



The Historical and Theological MSS. cannot be considered 

 of any great value. A great portion of Newton's later years 

 must have been spent in writing and rewriting his ideas on 

 certain points of Theology and Chronology. Much is written 

 out, as if prepared for the press, much apparently from the mere 

 love of writing. His power of writing a beautiful hand was 

 evidently a snare to him. And his fastidiousness as to the 

 expression of what he wrote comes out very curiously in these 



