6^ View of fame late Difcovenes and Improvements 

 compofing a great number of veffels of different calibres* in 

 which water, air, and various kinds of fluids drawn from 

 the bofom of the earth and the atmofphere, circulate. 



Light alfo has a great iufluence on vegetation. Hum- 

 boldt has ftiown that the light of a lamp may, in this re- 

 fpe£t, fupply that of the fun ; and that plants which receive 

 the light of a lamp are coloured green, as if they received 

 that of the fun. Excefs of light hurts plants, efpecially 

 when they begin to rife. 



According to Ingenhouz, plants fuffer oxygen to be dif- 

 engaged in the light, and the carbonic acid in darknefs. 

 Senebier is of opinion that the latter changes the oxygen in- 

 to the carbonic acid, by furnifliing it with carbon. 



Humboldt has obferved that mufhrooms furnifh hydro'- 

 genous gaz in the day, as well as the night-time. 



Medicine. — The carbonate of barytes and pure cauftic 

 barytic earth are moft active poifons. Pelletier killed fevefal 

 dogs by making them take from twelve to eighteen grains 

 of thefe fubftancea 



Mankind have been long employed in attempting to dif- 

 cover means for the prolongation of life. Valli, after lay- 

 ing down principles well known, viz. that old age comes oh 

 naturally, bccaufe the calcareous phofphate or calcareous 

 carbonate is continually accumulating in the greater part of 

 the folids, fuch as the bones, the arteries, veins, tendons, 

 &c. fays, that this accumulation can be guarded againft 

 only two ways ; either by preventing that fubllance from 

 being formed in the mafs of the fluids, or by expelling it as 

 foon as it is formed. 



1. To prevent too abundant a production of that earth, 

 one muft ufe aliments which contain the lead quantity of 

 it, fuch as vegetables, milk, fifh (but fifties contain a great 

 deal of the phofphoric acid). 



2. The means which he thinks moft proper for expel- 

 ling that calcareous earth, or calcareous phofphate, are, 

 bathing, fri&ions, diuretics, pure water, and beverages cooled 



with 



