1818.] different Varieties of Potatoes. 431 



and one insoluble in alcohol ; a number of small white brilliant 

 crystalline bodies were contained in it, amounting to about 12 

 parts in 1000 parts of the potatoe, which were found to be the 

 citrate of lime. The part of the extract insoluble in alcohol was 

 then more particularly examined, and was found to contain 

 several different ingredients ; 1 . A peculiar substance which 

 resembles animal matter in its characters, a minute quantity of 

 the substance that has been called asparagine, together with 

 the phosphates of lime and of potash, and the citrate of potash. 

 It is remarked that the resin and the animalized matter are the 

 only sapid ingredients of the potatoe, and give it the superior 

 flavour which is perceived when the potatoe is eaten roasted, 

 but which is necessarily lost by boiling. 



The following directions are given for the analysis of the 

 potatoe. 1. To bruize the potatoe, to squeeze it, and to add a 

 little water and again squeeze it strongly ; to collect all the 

 fluids, filter them, and afterwards boil them for some time. 

 2. To filter this liquor in order to separate the albumen, which 

 has been coagulated by heat, to wash it and to dry it in order 

 to know its weight. 3. To evaporate the liquor to the consist- 

 ence of an extract, to redissolve this in a small quantity of water, 

 in order to separate the citrate of lime, which must be washed 

 with cold water until it becomes white. 4. To dilute the liquor 

 with water, and to precipitate it by an excess of acetate of lead ; 

 to decant the fluid, to wash the precipitate repeatedly with cold 

 water, and to add these washings to the decanted fluid. 5. To 

 add a quantity of water to the precipitate obtained in the last 

 step of the process, and then to decompose this precipitate by a 

 current of sulphuretted hydrogen gas. 6. To filter the liquor and to 

 evaporate it to the consistence of a syrup in order to obtain the 

 citric acid in a crystallized state. 7. To precipitate in the same 

 manner by sulphuretted hydrogen the fluid decanted from the 

 precipitate. To filter the fluid, and evaporate it by a very gentle 

 heat to the consistence of a syrup, or rather of a soft extract ; 

 to leave it in this state for some days to enable the asparagine to 

 crystallize ; afterwards to mix up this matter with a very small 

 quantity of very cold water ; to let it settle, to decant the fluid, 

 and to wash it with small quantities of cold water until the aspa- 

 rasrine be rendered white. 8. To concentrate again this fluid to 

 the consistence of an extract, to treat it with alcohol heated to 

 8G°, in order to separate the acetate and nitrate of potash, and 

 to obtain the animalized matter as pure as possible. 



M. Vauquelin concludes his paper with the results of his 

 analyses of the 47 varieties of potatoes which were given him for 

 examination, indicating the amount of solid residuum contained 

 in each, and what part of this consisted of starch and of the 

 parenchyma. We have no means of ascertaining which of the 

 varieties that he employed are among those known in England, 

 as, excepting in three eases, the names which he employ, are 



