CONTENTS. 
Some further Observations on anew detonating Substance 321 
On a new systematic Arrangement of Colours eta 4 
Observations relative to the near and distant Sight of difs 
ferent Persons... 5. 00 ee oe eee Cal ee 2890 
An Appendix to Mr. Wane’s Paper on Vision ., 343 
The Correctness of popular Observations illustrated in the 
Directions commonly given for making Tea .  .. 345 
Additional Observations on the Effects of Magnesia in pre- 
venting an increased Formation of Uric Acid ; with Re- 
marks on. the Influence of Acids upon the Composition of 
Phe rine oi > vie | Sian ct e's wie) et ae 
A short Account of some Discoveries in Chemical Philosophy 
367 
Letter.from Dr. Wovraston on the Periscopic Construction 
of Spectacles ; with Observations ly M. Bior on a new 
Kind of Spectacles invented by Dr. WoLLASTON — 387 
Description and Use of an Instrument called ** The Secto- 
graph,” principally intended for the Purposes of dividing 
right Lines into equal Parts, measuring Angles, and in- 
scribing Polygons in the Circle, Sc. &c. 2. +... 401 
Some Experiments and Observations on the Substances pro- 
duced in different chemical Processes on Fluor Spar 407 
A new Theory of Light; with Eaperiments to prove that 
Blackness arises from the Reflection of Indigo and Red- 
orange on the seven prismatic Rays of Light .. 418 
Some Particulars respecting ihe present State of Persia 422 
On artificial. Cold wnat 25, SRR, SsaS 5 at eee 
On a saline Substance from Mount Vesuvius .. .. 495 
Final Letter from Mr.Wwm. Jones on Dr. WOLLASTON’S 
Periscopic Spectacle Glasses .. 0. se oe «s 464 
On: Galvanic Electricity sass. a.) “sak i ee 
Notices respecting New Books .. .. .. 69, 392,486 
Proceedings of Learned Societies .. .. 72,142,393, 479 
Intelligence and Miscellaneous Articles 76, 144, 224, 307, 
Z 399, 484 
Piast ry Waters SF ers, Js) oh e76, 495.1, Ree kegs. 
Meteorological Table .. 80, 160, 240, 320, 400, 489 
THE 
