AMYLUM MAKANT.^. C31 



lie be cautiously heated on the object-stage of the niicro.scope, tlie 

 tumefaction of the granules will be found to begin exactly at 70"^ C. 

 Heated to 100° C, with 20 parts of distilled water, arrowroot yields a 



transp 



By hydro- 



as 



chloric acid of sp. ot. 1*0G, arrowroot is but imperfectly dissolved at 



The specific gravity of all varieties of starch is affected by the water 

 which they retain at the ordinary temperature of the air. Arrowroot 

 after prolonged exposure to an atmosphere of average moisture, and 

 then kept at 100° C. till its weight was constant, was found to have lost 

 13'3 per cent, of water. On subsequent exposure to the air, it regained 

 its former proportion of water. 



Weighed in any liquid which is entirely devoid of action on starch, 

 > petroleum or benzol, the sp. gr. of arrowroot was found by one of us 

 to be 1*504; but 1'565 when the powder had been previously dried at 

 100^ C. 



Microscopic Structure of Arrowroot and of Starch in general. 

 The granules are built up of layers, — a structure which may be 

 rendered evident by the gradual action of chloride of calcium, chromic 

 acid^ or an ammoniacal solution of cupric oxide. When one of these 

 hquids in a proper state of dilution is made to act upon starch, or 

 when for that purpose a liquid is chosen whicli does not act upon it 

 energetically, such as diastase, bile, pepsin, or saliva, it is easy to obtain 

 a residue, which according to Nageli, is no longer capable of swelling 

 ^p in boiling water, nor is immediately turned blue by iodine, except on 

 the addition of sulphuric acid ; but which is dissolved by ammoniacal 

 ti'ipric oxide. These are the essential properties of cellulose ; and this 

 residue has been regarded as such by Nageli, while the dissolved portion 

 has been distino-uished as Granulose (Maschke, 1852). 



C. Nageli in his important monograph on starch ' has described the 

 action of saliva when digested with starch for a day, at a temperature 

 yf 40' to 47° C; he says that the residue is a skeleton, corresponding 

 m form to the orirrinal crrain but somewhat smaller, light, and very 



jjiobde in water. He concludes that its interstitial spaces must have 

 been previously filled with granulose. 



. This experiment, which has been repeated by one of us (F.), does not 

 in our opinion warrant all the inferences that Nageli has divawn from 

 *t : it is true that many separate parts of the grain are dissolved by the 

 saliva, while others have disappeared down to a mere film, and others 

 again have been attacked in a very irregular manner. But we cannot 

 "gi^ee with the statement that anything comparable to a skeleton of the 

 I'am has been left. After longer action at a higher temperature, which 



a 



nowevcr must not exceed 65" C, a more copious flissolution of tlie 

 •starch, either by saliva or by bile, takes place ; but in no case is it 

 complete. 2 



^^ Chemistry of Starch— Its composition answers to the formula 

 (e'H'"0-^)H 3 Off, or when dried at 100" C CH'^'O'. Musculus how- 

 ever sho^Yed, in 18G1, that by the action of dilute acids or of Dicstose, 



r 



\\r ^f ^(»^^r-f^-orncr, Ziiricli, 1S58. i", also may be found in my paper ^cter SUirle 

 >\. Nageli, Stdrl-enrvime, etc., Leipzig, und C,lUOo>^e-^Arvh>v dvr Pharvmar, 19G 

 ^8^'4- -J ii ' i ^ (1871) 7.--F. A. F. 



further particulars on this questiou 



