74 Scientific Intelligence. [July, 



Lectures ; in which it will appear that this illustrious philosopher 

 and his eminent friend Mr. Watt, are theoretically and experi- 

 mentally inimical to distilling in vacuo. 



Your constant reader, P. A. 



Mr. Watt " finds that water distils perfectly well, when of the 

 temperature 70°, and that, in this state, the latent heat of the 

 steam approaches to 1,300, and certainly exceeds 1,200. The 

 unexpected result of these experiments, is, that there is no 

 advantage to be expected in the manufacture of ardent spirits 

 by distilling in vacuo ; for we find that the latent heat of the 

 steam is at least as much increased as the sensible heat is dimi- 

 nished. This will undoubtedly be attended with an increased 

 expenditure of fuel ; for the increase of 100 degrees of sensible 

 heat occasions an increase of fuel only while we are raising the 

 temperature of the still to the ordinary heat of boiling water, in 

 the beginning of the distillation. If the furnace be judiciously 

 constructed, and due precautions taken to prevent dissipation, it 

 requires very little fuel to maintain this temperature. But 100 

 degrees of latent heat is an expense that is continual, and 

 which no contrivance whatever can prevent." 



On the subject of Mr. Tritton's method of distilling in vacuo, 

 the Editors beg to remark, that this gentleman does not, in his 

 letter, state the saving of fuel as an advantage likely to arise 

 from his process, but merely the improved quality of the fluid, 

 as being free from the unpleasant flavour which is apt to attach 

 to spirits distilled at a high temperature. The experiments on 

 the oils contained in different species of corn, mentioned at 

 p. 35 of this number, may probably throw some light upon the 

 point in question. 



IV. Newly discovered Membrane in the Eye. 



Dr. Jacob, Demonstrator of Anatomy in the University of 

 Dublin, has discovered, and demonstrated in his lectures on the 

 diseases of the eye, this spring, a membrane covering the exter- 

 nal surface of the retina, in man and other animals. Its extreme 

 delicacy accounts for its not having been hitherto noticed. He 

 arrived at the discovery by means of a new method of displaying 

 and examining this and other delicate parts. He argues from 

 analogy the necessity of the existence of such a membrane, as 

 parts so different in structure and functions as the retina and 

 choroid coat must otherwise be in contact, in contradiction to 

 the provisions of the animal economy in general. A detailed 

 account of the discovery, with the method of displaying the 

 membrane, is in preparation, and will shortly be laid before the 

 public. 



V. Plate presented to Dr. Paris. 



-On Tuesday the 16th instant, a deputation of noblemen and 

 gentlemen, of the county of Cornwall, waited upon Dr. Paris, at 



