CONTENTS. • ix 



Mathematical Correfpondence — — ~" P- 45 



Scientific Ne«s — — •— — p. 46 



Revival of the Journal des Savans aud the Annales de Cbltnie. Sitting of the French National In- 

 ftitute. Accounts of foreign buuks. 



M A Y 1797. 



I. Extraft of a Memoir concerning three different Species of Carbonated Hydro- 

 genous Gas obtained from Ether and Alcohol by different Froceffes, forwarded 

 to the National Inltitute of France by the Society of Dutch Chemills ; being 

 Part of a Report read to the Fiift Ciafs of the Inftinitc bv Citizen Fonrcroy, 

 at the Sitting ot the 26th Frimiire, i6th December 17^6 [concluded] p. 49 



Purification of defiant gas — Pliyfical properties^negative — affords an oil when mixed with oxyge- 

 nated muriatic acid gas — Properties of this oil. Coinpolition of the olefiant gas. It contains hy- 

 drogene and carbone. Appropriate name. Oleliant gas from ether treated with fulphuric acid, 

 or from alchol and ether paffed thr nigh an ignited tube of pipe clay. Gas afforded by palTing ether 

 and alcohol through an ignited g'afs tube — Is not olefiant, &c. Various experiments. Two other 

 elaltic fluids obtained from ether and alcohol. Recapitulation. Quellions and enquiries relating 

 to theory. 



II. On the Methods of obviating the Effefts of Heat and Cold in Time- 

 pieces — — — — — P- 5^ 



Inftruments for meafuring time. Hour-glafs — Sand-clock — Water-clock — Common clock and watch- 

 Trains of wheels — move uniformly when acted upon by a weight, becaufe friftion prevents the ac- 

 celerated motion. Of clocks regulated firfl by a fly — then by a balance — and laftof all by a pen- 

 dulum. Detached efcapements and compenfations for temperature. Effe£l of temperature on 

 docks. Deal pendulum. Graham's quickfilver pendulum — improved by Troughton. Harrifon's 

 gridiron pendulum. Ellcot's lever pendulum — improved by Gumming. Fixed compenfations. Pro- 

 jeift for a gridiron balance. Curious contrivance ot a compound bar which bends when its tem- 

 perature Is changed. Theoretical and practical confiderations. Experiments with a bar of this 

 kind. The expanfion balance defcribed. Application of the fame principle to pendulums, In- 

 ftruiSion to aftual workmen, _ .. 



III. Obfervations and Experiments on the Light, Expence and Conftrudlion of 

 Lamps and Candles, and the Probability of rendering Tallow a Subltitute for 

 Wax — — — — — P> 67 



Artificial light is an objeft of the firft necedity — means of producing it — meafure of its intenfity. 

 Obfervations on lamps — purification of oil— accefs of air — inconvenience of lamps. Obfervations 

 on the candle. — Fulibility, or freezing points of tallow, fpermaceti, fatty matter of flefli, pela, 

 bees-wax and bleached wax. A lamp for tallow, very defirable. Experiment. — Confiderations 

 rcfpeding the fnuffing of candles. Chincfe candle with wax on the outfiiie. Imitation. Expe- 

 liments for rendering tallow lefs fufible. 



IV. A Memoir upon the Difcovery of America. By Mr. Otto — p. 73 



latroduAory rcmarkt, Hillorical documents refpe£ling Martin Buhem — ^who failed in 14S4 from 



Portugal, 



