574 Mr. Warington on the 



degree may be reduced, as I showed some years ago in my 

 Mathematical Researches* . 

 Long Stratton, Norfolk, May 1, 1845. 



l^XXXI. On the Distilled Waters of our Pharmacopoeias. 

 By Robert Warington, Esq.-\ 

 'I'^HE subject of flavoured waters, prepared by distilJation 

 -*■ or extemporaneously, through the medium of carbonate 

 of magnesia, has for some time past engaged my attention ; 

 and as it is a question of considerable importance to the phar- 

 maceutical chemist, I am induced to lay the detailed investi- 

 gation before the Society. 



The formulae given for the preparation of distilled waters 

 in the London Pharmacopoeia of 18^6 is as follows: — To a 

 specified quantity of material, whether it be essential oil, 

 flowers, herbs, bark or berries, let 2 gallons of water and 7 

 oz. of proof spirit, having a specific gravity 0*920, be added, 

 and submit the mixture to the process of distillation until one 

 gallon shall have passed over. Presuming that the entire 

 amount of spirit employed passes over in this operation, the 

 resulting product will contain a quantity that will be equiva- 

 lent to about 4^ oz, of rectified spirit of spec. grav. 0'8'^8, 



The Edinburgh form has rather less spirit to the propor- 

 tion of materials, 2 gallons of water and 3 oz. of rectified spirit 

 are so employed, and a gallon distilled. 



The Dublin formula differs from the foregoing, in ordering 

 half an ounce of rectified spirit to be added to each pound of 

 the water after distillation, or in the ratio of 5 oz. to the gallon. 

 In the course of other investigations, some years since, I 

 found that when a very small quantity of alcohol was added 

 to distilled water, and the mixture kept exposed to the air for 

 a length of time, the containing vessel being carefully covered 

 with paper to exclude the dust, it became gradually converted 

 into acetic acid, and, by analogy, I was led to believe that the 

 same effect would take place in these distilled waters ; the fol- 

 lowing experiments were therefore put in operation to test the 

 accuracy of these ideas. 



In the distillation of essential oils, it is vrell known that the 

 water which passes over is opalescent from its being highly 

 charged with the oil, and that when thus impregnated, it will 

 keep perfectly sound for a great length of time. Pistilled 

 waters were prepared from various of the essential oils without 

 * See Sir W. R. Hamilton's Inquiry on tlie subject in the Sixth Report 

 of the British Association for the Advancement of Science, 



t Communicated by the Chemical Society j having been read January 

 20, 1845. 



