20 CATALOGUE OF NEWTON PAPERS. 



as the most fusible an alloy of 5 of lead + 7 of tin + 12 of bismuth. 

 April 1693 and June 1693, further experiments. 



9. April 1695. Experiments with antimony and ores of iron, 

 copper, and tin, and sublimations with salammoniac. Feb. 1695 6, 

 sublimations of antimony with iron ore. 



10. Notes of Chemical Experiments, without date: 

 Action of aqua fortis on antimony sulphide, &c. 

 Sublimation of alloy of antimony and lead with salammoniac, &c. 

 Experiments on lead ore and other things. 



Do. on copper &c. 

 Other experiments. 



11. De metallo ad conficiendum speculum componendo et fun- 

 dendo. Printed by Brewster, ii. 535. 



V. MISCELLANEOUS NOTES. 



1. Notes on Magnetism. It does not appear whence they are 

 taken. The observations (some of which are erroneous) do not seem 

 to be Newton's, though here and there remarks upon them seem to 

 be his. 



2. De Natura Acidorum, with a copy. This is printed in 

 Horsley's Newton, iv. pp. 397400. 



3. Eleven points for enquiry in Physics. 



4. De Gemmis in genere, notes, mostly from Berquen, Boethius, 

 Tavernier, and Boyle. Index of refraction in diamonds is given 

 -3^ on the authority of Halley. On p. 3 is mentioned a very 

 fragile and soft western Topaz which he found to have a specific 

 gravity 4.27, though the sines of refraction were as 14 to 23 (could 

 this be Baryte ?). On p. 7 he deduces from the cleavage that gems 

 are crystallized like salts from juices which turn to stone. At the 

 end are the gold and silver standards of different countries. 



5. De Gemmis. Other notes mostly included in the preceding, 

 but on p. 1 are given reasons for thinking the diamond coagulated 

 from a fluid and fat substance, which he does not seem to have in- 

 corporated in the preceding. 



6. Of Gemms. Part of the foregoing in English. 



7. Extracts from Berquen. 



8. Odd notes 011 gems. 



9. Gemmarum pretia. 



