^EW METAL IN CRUDE PLATINA, &C. 117 



the meridian of London,) its return to that place in 180t ac- 

 cording to Mayers tables improved, is Dec. 13th. 0^- 19™- 36* 

 the interval, (allowing for bifTextiles, &c.) is 6114.16"- 12*^ 

 40'"* 56** which divided by 1674, the number of years, gives 

 365^- 5^'49'^' 42" Now the obliquity of the ecliptic, as ob- 

 ferved by Caffini in 1655, and Flamftead in 1689, being com- 

 pared with that obferved by Horn{by in 1772, Mafkelyne in 

 1769, Bradley in 1750, and Mayer in 1756, and a mean of 

 their obfervations taken, will give for the decreafe of the ob- 

 liquity of the ecliptic 59'' per century, or 35 ^'^4. per year. Ac- 

 cording to thefe calculations the obliquity of the ecliptic for 

 1 804 will be about 23^ 27 '49''; then as the fun moves over this 

 fpace in one quarter of a year, fay as 23° 27' 49" is to J of the 

 given year, fo is the decreafe of the obliquity of the ecliptic* 

 per year 35'''4 unto 55^\ which taken from 365°' 5^' 49"* 42* 

 gives for the length of the folar year 365°' 5^- 48'"' 47'- and the 

 time the fun moves over the proceffion of the equinoxes is 20 

 minutes 27 feconds, which being added to the folar year will 

 give 365°' 6^- 9". 14" for the length of the fidereal year. 



But by afluming I of the year thus found, and working as 

 before, it will give the length of the year more accurately. 



V. 



ExtraSis from a Letter of R. Chenevix, Efq. P. R. S. from 

 Drefden, to Charles Hatchett, Efq. F, R, S. containing Infor^ 

 mation refpe^ing the new Metal contained in Crude Flatina ; 

 Beet Sugar ; the non-exiftence of Agvjlile as a peculiar Earth; 

 and a Defcription of a new Furnace for Chemical Operations, 

 Cofumunicaied by C. Hatchktt, Efq, 



I SUPPOSE you have heard of the new metal contained in New metal In 



cruce platuii* 

 raw platma. Here is what Berthollet has jult written to me 



upon the fubjed : 



<* Des Coftils diffblves raw platina in nitro-muriatic acid, 



and precipitates it by muriate of ammonia at feveral times; 



the firft portions are yellow, the laft redder. He reduces the 



red precipitate, and obtains an alloy. He expofes this alloy to 



a current of oxygen, and a blue oxide is volatilizedj pure 



platina remains behind. The blue fublimate is the oxide of his 



new 



