1847.] Mode of Feeding Cattle. 227 



duce a system which would go on annually increasing the amount 

 of their produce, and consequently the amount of their profits. 

 This would enable them to farm higher, and, by farming high, 

 they would keep that place which, he was sure, they now occu- 

 pied in the history of the world. He would likewise direct their 

 attention to the use of linseed, and the preparation of food, as 

 being of great value in keeping working animals in good condi- 

 tion; but on this point he would not detain them by giving a 

 special detail of facts, as the same general principles apjjlied in 

 the one case which applied in the other. As he had occupied thj 

 attention of the meeting at considerable length, he would conclude 

 for the present, reserving any additional remarks which he had to 

 make, and the replies to any questions which the company might 

 think he could usefully answer, until after the general discussion 

 was ended. 



REMARKS ON THE FORMATION OF CRYSTALS OF 

 ARGENTIFEROUS GALENA, BY SUBLIMATION. 



BY C. T. JACKSON. 



At the meeting of the American Association of Geologists and 

 Naturalists at Boston, New Haven and New York, I proposed to 

 account for the origin of several metalliferous veins, by sublima- 

 tion of their ores or constituents. In favor of this theory, I men- 

 tioned that a considerable loss was sustained in smelting lead ores, 

 owing to the evaporation of the s jlphuret of lead at the temperature 

 required for its redaction; and called the attention of geologists to 

 the quantities of sulphuret of lead which rise in the chimneys of 

 smelting works, and to the particles of sulphuret of lead which fall 

 on the roofs of the buildings, and on the surrounding soil. 



It was ascertained by Berthier, that when galena is kept fused 

 in a crucible, lined with charcoal, in which the reduction of the 

 lead could not take place, a considerable portion of the galena 

 was ac'aally lost by sublimation. It is also known, that although 

 silver is regarded as fixed in the fire, and does not volatilize when 

 exposed for weeks to the heat of a porcelain furnace, it is partial- 

 ly sublimed with the vapor of lead in the process of cupellation ; and 

 that the last portions of litharge blown over, contains a notable 

 proportion of silver. 



It appears probable, that argentiferous galena is also volatile 

 unrler certain circumstances; and from some phenomena which I 

 observed at the Shelburne mines, and in the crystals of lead ore 

 which I have examined, it would seem that the origin of those 



