On the Coviet of \SOf\ 6f 



15 grains* As I had been obliged to filter the liquors and 

 to dry the filters, I thought that the camphor not dissolved 

 must have lost its weight by evaporation, and that the ba-* 

 lance did not give me the just quantity absorbed by the 

 water ; I therefore sought for a reagent, which evinced to 

 me the presence of camphor in the water. -.» 



I found that potash precipitated the camphorated wat«r^ 

 while soda or ammonia did not affect it; i^ut the potash 

 must be pure and caustic. If it contains carbonic acid, it 

 docs not precipitate the can^phor ; and if after having pr^* 

 4ipitated it we expose the vessel to the air, the liquor absorb* 

 ing carbonic acid resumes its transparency. w/vi ::d 



Here, therefore, is a new method of distinguishing^jjbt- 

 ash from soda. Camphorated water is in this respect A 

 more certain reagent than the nitro-muriate of platina, and 

 more easily procured. But the metallic salt is more con- 

 venient, as it precipitates the carbonate of potash. 



On trymg by caustic potash camphorated water charged 

 1^'ith carbonic acid, I obtained no precipitate, except by put- 

 litig in a great excess of alkali : this precipitate did not seem 

 to be greater than tliat obtained in distilled water. I think| 

 therefore, . that carbonic acid does not sensibly favour the 

 Solution of camphor in water ; but it at least results from 

 these experiments, that the water does not merely charge 

 itself with the aroma of the camphor, as some chemists think, 

 and that this concrete volatile oil is dissolved in a proportion 

 lufficient for the purposes to which it is applied. When 

 the camphor is reduced very small by trituration with some 

 drops of alcohol, water takes up more of it than 1 6 grains 

 fet pint, and some chemists have dissolved even 30 grains. 



XV. Letter from Gavin Lowe, E^q., on the Comet 

 of 1807. 



To Mr, TilhcL 



JL HE comet that made its appearance about the latter 6nd 

 of last September, and continued visible during the thretf 

 Succeeding months, has no doubt been carefully and ^issi- 

 duously observed by the astronomers, not only ia this coim- 



K 2 ^ uy. 



