MERINO WOOL, J21 



fupceeded when circumstances were not sufficiently favourable 



for the success of the other. 



I have applied a method, similar to those just described, to the Water frozen, 



freezing of water, by means of the ingenious instrument ima- J^ *? r p p l ," mp 



gined by Dr. Wollastotv*, tp which he has given the name of to Dr.Wollaf- 



chryophorus. This, instrument consists ip a tube, terminated at tons ins ^ ru ~ 



ment. 

 each extremity by a ball, like the common pqlse glass, one of 



these being full of water, and both the balls and tubes 

 being completely exhausted of air. By plunging the empty 

 ball into a mixture of salt and snow, the water in the 

 other ball, though at some inches, or even some feet distance 

 from the cold mixture, is frozen in a few minutes. But by 

 a process, similar to that I have just described, for the congela- 

 tion of mercury, the same may be effected without any cooling 

 mixture in less than one minute, and with a pump of very mo- 

 derate power. I may take this opportunity of mentioning, that 

 having constructed an aparatus of this kind, with a thermome- 

 ter within it, I observed that the temperature of the water 

 sunk to 20° ; and, in one instance, even two or three degrees 

 lower before it froze, which I at first ascribed to the water 

 b?ing deprived of its air by previous boiling ; but the same cir- 

 cumstance not having uniformly taken place, when the shape 

 and size of the apparatus, and the quickness of the process, 

 were varied, I am now inclined to ascribe it to other 

 causes. 



I have the honour ro be, &c. &c. &c, 



ALEXANDER MARCET. 

 Russell Square, 22nd Jan. 1813. 



vir. 



Observations upon the best state in which it is advisable to 

 bring the British Merino Wools to market. By Edward 

 Sheppakd, Esq. of Uley, in Gloucestershire. 



MR. SHEPPARD lias made his title good to that fame Introduction, 

 which attends the patriotic and well-directed exertions 



* This apparatus was described a few weeks ago, by Dr. Wollaston, 

 in a paper which was read before the Royal Society, an abstract of 

 which was published in the 1st number of Dr. Thomson '$ Annals of 

 Philosophy. 



Of 



