102 On Citric Acid. 



It would be improper to dismiss this subject before we speak 

 of the application and general uses of the citric acid. 



Besides the medicinal* uses to which the citric acid is applied, 

 such as the making of saline draughts, &c., it is often combined 

 with opium to prevent the stupifying effects of that very power- 

 ful narcotic ; and I have been told that it has been given with good 

 effect to counteract such an over-dose of it as would otherwise 

 have proved fatal. In domestic ceconomy the citric acid is em- 

 ployed with advantage as a condiment for a variety of food, it 

 being more grateful than vinegar on account of the fine aroma 

 derived from the essential oil peculiar to the rind of this fruit. 

 Likewise for taking out iron-moulds or other stains of iron ; as 

 this metal is not only soluble in citric acid, but the solution is so 

 permanent that it is not precipitated again by the application 

 of soap, which sometimes happens when other salts are used for 

 this purpose. It is useful also for removing spots occasioned by 

 alkalies, or the alkaHne earths, from scarlet cloth ; — for making 

 a solution of iron for bookbinders, to give the mottled appear- 

 ance to the surface of calf-skin ; — for improving that peculiar 

 solution of tin which is employed for producing the most exquisite 

 specimens of the scarlet dye; — for altering the hue of some colours 

 which are used in the dyeing of silk ; — for the preparation of the 

 best Morocco-leather ; — for improving candles, by whitening and 

 hardening the tallow which is employed in making them. 



A very considerable quantity of citric acid, in the state of le- 

 mon-juice, is also consumed by the seamen of the British navyf . 

 It was formerly bought in this market, having first been submitted 

 to the judgement of a respectable chemist, who was regularly 

 employed for the purpose. As the managers of this depart- 

 ment have found that it can be brought from Sicily at a much 

 more reasonable price, and of the best quality, they now procure 

 it from that island, and decline all other sources. To preserve it 

 on long voyages, about ten gallons of brandy are generally put 

 to every 100 gallons of juice, which has the effect of precipitating 

 the mucilage, that otherwise would not fail, during a voyage, to 

 throw the whole into a state of fermentation, and convert much 

 of it into vinegar. Dizc?, in his Memoir read to the Institute of 

 France, says, that a lemonade of the most agreeable taste and 

 appearance may be made by dissolving forty grains of citric acid 

 in a pint of water, with the addition of a sufficient quantity of 

 refined sugar, and that it may be rendered fragrant by dissolving 

 \n it a small quantity of oleosa cchanim, prepared by rubbing a 



* It is said that altliough citric acid curdie the milk of most animals, it has 

 jiot thit eflect on woman's milk, whether used hot or cold. 



f Lord Anson and C.iptain Cook were, I understand, the first navigators 

 r.ho employed lemon-juice on their ships' crews for the prevention and cure of 

 ihc sea-scurvy. 



lertion 



