170 Mr. Cooper on an Improved Apparatus for [March, 



Article III. 



On an Improved Apparatus for the Analysis of Organic Products. 

 By Mr. J. T. Cooper .* (With a Plate.) 



An easy and accurate method of determining the ultimate 

 elements of bodies composed of carbon, hydrogen, oxygen, and 

 azote, has been of late years a great desideratum among chemists, 

 as such a variety of contrivances have been suggested by scien- 

 tific individuals, all of which have their peculiar merits and 

 defects. It is presumed the instrument and method of operat- 

 ing now presented to the Society and the public, if not entirely, 

 may be considered as nearly free from those objections which, in 

 my opinion, may be fairly urged against those heretofore in use. 

 It might, however, be considered ungenerous, was I to take upon 

 me the task of pointing out those defects, I shall therefore con- 

 tent myself by briefly stating in this communication, the class 

 of substances to which it is applicable with a view to determin- 

 ing the proportions of their elements, and a description of the 

 method of operating upon each of them. 



As this apparatus seems more particularly calculated than any 

 other for operating on volatile matter, such as the essential oils, 

 camphor, benzoic acid, and a variety of similar substances, I 

 shall in the first place describe the method I have adopted in the 

 analysis of this class of bodies ; and when it is considered that 

 I write not for those who are accustomed to the more minute and 

 delicate operations of chemical analysis, but for those who are 

 or may be considered as unacquainted for the most part with 

 this subject, I hope I may not be considered as tedious should I 

 venture to give those directions which to the more matured in 

 science may seem to be unnecessary. 



The oxide of copper used in the experiments is best procured 

 from the residuum of verdigris (binacetate of copper), which is 

 or was used to be distilled in glass retorts for the preparation of 

 strong acetic acid. The reason I prefer the oxide of copper 

 prepared by this process over any other is, that it is more likely 

 to be free from impurity than that which is prepared by precipi- 

 tation from acid solutions. Every one who is in the habit of 

 preparing precipitates knows the difficulty there generally is in 

 freeing considerable quantities of precipitated matter from adher- 

 ing neutral salts ; and as the smallest impurity would in some 

 measure contaminate the result of the analysis, it is a very 

 necessary precaution that the oxide, which is by far the greatest 

 in quantity of any substance that is employed in the operation, 

 should be perfectly pure. Should it however happen that at any 



* From the Transactions of the Society for the Encouragement of Arts, Manu- 

 factures, &c. Vol. 41. 



