OXALIC ACID. 45 



may be observed, in the alcoholic extract, a sediment insoluble in 

 water, which consists of the most beautiful crystals of this salt. 

 While in the acid urinary fermentation the separation of the oxalate 

 of lime increases with the augmentation of the free acid of the urine, 

 in the latter case the salt is separated by the removal of the free acid. 

 The quantity of oxalate of lime in ordinary urine is so minute, 

 that, till recently, chemists, from the want of sufficiently accurate 

 means of analysis, were unable to recognise it; good analysts 

 have, however, always found, in the insoluble part of the ash of 

 the extract of urine, a little carbonate of lime, which, at all events, 

 owes part of its origin to the oxalate of lime. 



Crystals of oxalate of lime are most frequently found in the 

 urine after the use of vegetable food, especially of such kinds as 

 contain ready formed oxalates (Wilson.*) Donne found that after 

 the use of sparkling wines, the quantity of the salt is increased in the 

 urine ; and my own experiments show that there is an increased 

 secretion of oxalate of lime after the use of beer containing much 

 carbonic acid and of the alkaline bicarbonates and vegetable salts. 

 I cannot confirm Bird's view that highly nitrogenous food causes 

 a precipitate or even an augmentation of the oxalate of lime. It is 

 often found in the urine of pregnant women. (Hofle.)t 



From a series of direct experiments on the subject, C. SchmidtJ 

 is led to deny that oxalate of lime introduced into the stomach, 

 passes into the urine; and in this point I can perfectly confirm 

 him, without, however, going so far as to assert that the food exerts 

 no influence on the formation of this body. In the excrements of 

 caterpillars we often find much oxalate of lime which is not formed 

 directly from the ingesta, since I have very often found the crystals 

 in the biliary ducts of these animals. Preparations can be easily 

 made of these organs, and in consequence of their contractility a 

 large quantity of their contents may be expressed from the cut 

 tubes, and submitted to microscopic examination. 



With reference to the occurrence of oxalate of lime in certain 

 morbid conditions, Prout, Bird, and others, make very different 

 statements, none of which are yet fully established. Numerous 

 examinations of morbid urine have convinced me, that in this 

 country, at least, the sediments of oxalate of lime are much rarer 

 than they are represented to be by English writers. These inves- 

 tigations have led me to the following results ; when the respi- 



* Provincial Medical and Surgical Journal, 1846, p. 413. 



f Chemie u. Mikroskop u. s. w. S. 385. 



J Entwurf u. s. w. S. 70. 



Jahresbericht d, ges. Med. 1844. S. 25. 



