Chemcfll Science* 465 



smaller horizontal ones at right-angles, and to these, vertical 

 tubes of four feet each were attached, terminated by a bell- 

 glass, which enclosed about an inch of the cylindrical glass of 

 the burners. In a few months I found this plan very ineffi- 

 cient; the current through the tubes, in consequence of the nu- 

 merous angles, was too slow to carry off more than a very 

 small portion of the vapour, and the tubes became leaky by 

 corrosion : I then ordered a leaden tube to be fixed by a curved 

 joint, to the vertical tube immediately over the burner, and 

 suffering it to pass horizontally about three feet, I directed it to 

 be turned vertically downwards, with a curve at the angle, to 

 the length of nine feet, through the floor of my shop into the 

 cellar. 



I was repeatedly assured by the maker of my apparatus, 

 who is one of the fitters, that my plan could not answer, be- 

 cause the column of cold air in the long tube would be more 

 than an equivalent for any rarefaction that could take place in 

 the four-feet tube over the burner. I persevered, however, in my 

 determination to make the experiment, and it succeeded be- 

 yond my expectation. I have found it necessary to have a se- 

 parate tube to each burner, but I consider this expense well 

 repaid by the advantage derived. The current through the 

 tubes is so strong, as instantly to blow out a candle at the lower 

 end, when the gas is burning ; and so complete is the conden- 

 sation, that two ounces of water per hour is produced from 

 each light The water thus obtained is perfectly bright, and 

 not unpleasan: to the taste, nor does it exhibit any impurity 

 except a slight portion of sulphuric acid. The fitter, who so 

 obstinately opposed my plan, informs me, that he has put up 

 similar apparatus since mine, with complete success. 

 I am, Sir, your most obedient Servant, 



Wm. B. Hudson. 



III. Natural History. 



1. Medical Prize Questions. — The question proposed by the 

 Cercle Medical of Paris, in 1819, not having been treated in a 



