76 ANIMAL BASES. 



They give a process for procuring it, and describe its properties 

 at considerable length, though they did not succeed in obtaining 

 it in a state of purity. 



In the year 1798, Dr Rollo published his cases of Diabetes 

 Mellitus. To the second edition of this work was added an ap- 

 pendix by Mr Cruikshanks of Woolwich on Urine. In this 

 very important paper Mr Cruikshanks, who seems to have been 

 ignorant of what Rouelle had done, describes urea anew, and 

 gives a much more detailed account of its properties. Fourcroy 

 and Vauquelin take no notice of Cruikshanks in their paper, 

 and might have been supposed ignorant of the discoveries of the 

 British chemist, had not Fourcroy added copious notes to the 

 French translation of Hollo's work, and must therefore of neces- 

 sity have been acquainted with that book. In his Systeme de 

 connaisanqes Chimiques, published about the beginning of the 

 present century, he notices Cruikshanks's discoveries, and parti- 

 cularly the property which urea has of combining and crystal- 

 lizing with nitric acid ; but blames him for calling it animal ex- 

 tractive matter instead of distinguishing it by a peculiar name. 

 In the elaborate paper upon Urine by Fourcroy and Vauquelin, 

 published in 1800,* they notice Cruikshanks's discoveries; but 

 assure their readers that they had discovered urea and ascertain- 

 ed its characters, a whole year before they became acquainted 

 with Rollo's work, in consequence of the notice of it in the Bi- 

 bliotheque Britannique. 



Neither Rouelle, Cruikshanks, nor Fourcroy and Vauquelin, 

 had obtained urea in a state of purity. But in 1 808 Berzelius 

 published the second volume of his Djurkemien in which he de- 

 scribes a process, rather complicated indeed, but successful, by 

 which he obtained it in a state of purity, and was enabled to deter- 

 mine its properties.! But, as this book was written in the Swe- 

 dish language, the discovery of Berzelius remained unknown till 

 his View of the Progress and present State of Animal Chemistry 

 was published in English in 1813. 



In 1818, Dr Prout published his Observations on the Nature 

 of some of the Proximate principles of Urine.\ In this important 

 paper he gives a much easier and shorter process for obtaining 



* Ann. de Chim. xxxi. 48, and xxxii. 80. 



f Forelasningar i Djurkemien, ii. 279. 



\ In the eighth volume of the Medico- Chirurgical Transactions. 



