APPARENT ENLARGEMENT OF THE MOON. 139 



6th. That, notwithftanding thefe differences, it is not the 

 lefs a beautifnl new fpecies of this immediate principle of 

 vegetables to chemifb; and, that it is to be wifhed that phy- 

 ficians would try it, to afcertain whether, as there is reafon 

 to believe, its action will be the fame on the animal eco- 

 nomy. 



7 th. That, during the operation from which this camphor 

 refults, there is formed a true combination of muriatic acid 

 and volatile oil, having a refemblance to what the ancients 

 called acid foaps. 



8th. That liquid muriatic acid, and dilute fulphuric acid, 

 not mixing with oil of turpentine, their a&ion is confined to 

 their point of contacl. 



9th. That the mode of action of the muriatic gas, in this 

 circumftance, may be explained by the elegant theory which 

 MM. Fourcroy and Vauquelin have given of the a&ioa of 

 fulphuric acid on vegetable fubftances in general. 



10th. That, notwithftanding camphor is fet free by the 

 flow diitillation of oil of turpentine, without addition, we are 

 led to believe that fo large a quantity of this matter could 

 not exift ready formed in it, and that at lead a part is the 

 refult of the re-a€tion of the principles of the oil, excited by 

 the prefence of the acid gas, and its affinity for water. 



11th. Finally, that the fame procefs is not applicable to the 

 extraction of the camphor contained in the volatile oils of 

 lavender and rofemary. 



XVI. 



Letter from Joseph Huddart, Efq. F. R. S. on the apparent 

 Enlargement of the Moon at low Altitudes. 



To Mr. NICHOLSON. 

 Dear Sik, 



AT was not until yefterday that I received your Journals, Introduction. 

 Nos. 36 and 37 : In the former, reading a letter from C. L. 

 occafioned my referring to No. 35, page 164, of the Journal, 

 for Mr. Walker's letter refpecling the fenfible magnitude of 



the 



