- Intelligence and Miscellaneous Articles. 235 



operation is to be repeated till all the soluble matter is dissolved. The 

 residue is then to be drained on a cloth and dried in a water-bath. 

 M. Guerin remarks that Dr. Thomson has confounded that part of 

 cherry-tree gum and native gums which is insoluble in cold water, 

 with gum tragacanth, under the common name of Cerasin ; but they 

 ought to be distinguished, for the insoluble part of native gums yields 

 nearly the same proportion of mucic acid as arabin, whilst bassorin 

 gives more j the former also is dissolved and changed into arabin by 

 boiling water, whilst the latter suffers no alteration by it. The name of 

 cerasin is reserved by M. Guerin for that part of native gums which 

 is insoluble in cold water, and he thinks that it may be considered as 

 isomeric with arabin. 



One hundred parts of cerasin consist of 



Cerasin 90*60 



Water 8*40 



Ashes 1 '00 



100* 

 The ultimate analysis of cherry-tree gum, which contains nearly 35 

 per cent, of cerasin, differs scarcely at all from that of gum arabic. 

 Cerasin is insoluble in alcohol, and does not undergo the vinous 

 fermentation ; it swells slightly in cold water, without dissolving. A 

 quantity of cerasin was boiled in water during six hours ; the trans- 

 parent liquor obtained was evaporated to dryness in a platina capsule. 

 The residue was composed of 



Arabin 90-587 



Water 8*402 



Ashes 1011 



100* 

 M. Guerin found that water at 65° Fahr. dissolved 13*15 per cent, of 

 it, and at 212°, 19*03 ; and he considers the cerasin as converted into 

 arabin by the action of the heat, and this transformation he thinks may 

 be accounted for, by considering the circumstances under which gums 

 are formed. Gum arabic and Senegal flow from certain trees in hot 

 countries, which probably occasions the formation of arabin ; while 

 in colder climates cerasin is formed, which by the heat of boiling water 

 becomes arabin. 



The following are given by M. Guerin as the composition of the 

 gum of the annexed trees. 



Apricot. Plum. Peach. Almond. 



Arabin and cerasin 89*85 82*23 82*60 83*24 



Water 6*82 15*15 14*21 13-79 



Ashes 3-33 2-62 3*14 2-97 



100- 100* 100* 100- 



EXAMINATION OF SUGAR OF MILK. 



M. Guerin remarks that gum and sugar of milk are the only sub- 

 stances which by being heated with nitric acid yield mucic and ox- 

 alic acids ; and he thought it desirable to ascertain which of them 



2H2 



