Ohfervathns on the Freezing of IValer, ^c. 249 



other circiimrtances being alike, the lofs or wafte of metal 

 will alfo be in the fame ratio. 



There are, however, other fafts not unworthy of notice. 

 No. I. pig-iron^ or richly carbonated metal, when ran from 

 an air-furnace, will be found in point of quality little better 

 than No. 11. or carbonated iron. This is owing to a quan- 

 tity of its carbon being deftroved during tbe fiifion. The lofs 

 in melting No. I. iron, therefore, chiefly coniills of carbon; 

 and the deficiency of metal ought never, with a clean bot- 

 tom, to exceed i cwt. in 20. 



Carbonated or No. H. iron alfo becomes deprived of a 

 confiderable portion of its carbonaceous mixture in fufion ; 

 and when run from the air-furnace is feldom better than 

 No. II[. metal. The lofs fuflained in melting may be ave- 

 raged at 7^ per cent. 



No. III. pig-iron is, after melting in an air-furnace, found 

 whitilh or mottled. It is feldom fufceptible of the lame nice 

 degree of divifion as the fuperior qualities, and lofes in fufion 

 a much larger proportion of metal, feldom under 10 per cent, 

 and frequently 12' or 15. 



The quantity of coals requifite to melt a given quantity of 

 iron is various, as much depends upon the quality and tufi- 

 bilitv of the metal. If the furnace goes one heat a day with 

 No. I. or II. iron, the quantity of coals will be from 20 to 

 45 cwt. for a ton of iron. If two or three heats a day, or as 

 many tons of iron are melted at one kindling, the proportion 

 of coals will be nearly weight for weight of »he iron melted 

 when the coals are mixed with a fair proportion of Imall : 

 with ftrong large fplint coals, one ton of good pig-iron may 

 be completely reduced with from 12 to 15 cwt. including the 

 previous heating of the furnace. 



XTjIV. Ohfervathns on the Freezing of JVater and the Na- 

 ture of Snoiv : in a Letter fr(jm Profeffor DniEHSEisi to 

 Dr. Van Marum*. 



XxS the prcfent fcafon has afforded us an opportunity to 

 make experiments on the freezing of water and the nature of 

 fnow, I flatter myfelf that it will give you fome faiisfa*ition 

 to be made acquainted with the rcfults I have obtained in 

 regard to lliis important iubjec^; and I give you full liberty 

 to publifli them, if you think they are likely to be of any 

 uiility. 



" From Algcmeene Konjl rn Lc/ifi'Bot<-, No. 14, icoj. 



At 



