The following is the theoretical percentage composition of the digitalins, the identity of which has been fairly established. They are arranged according to their percentage in carbon:—
TABLE SHOWING THE COMPOSITION OF THE DIGITALINS.
| Name. | Formula. | Percentage Composition. | |||
|---|---|---|---|---|---|
| Digitalein, | C21H46O11 | C. 53·16 | per cent. | H. 8·08 | per cent. |
| Digitonin,[561] | C31H52O17 | C. 53·44 | „ | H. 7·46 | „ |
| Digitalin, | C54H84O27 | C. 58·16 | „ | H. 3·65 | „ |
| Digitaletin, | C44H30O18 | C. 62·41 | „ | H. 3·54 | „ |
| Digitoxin, | C21H32O7 | C. 63·63 | „ | H. 8·08 | „ |
| Digitaleretin, | C44H38O18 | C. 66·05 | „ | H. 4·58 | „ |
| Paradigitaletin, | C44H34O14 | C. 67·17 | „ | H. 4·3 | „ |
[561] According to Kiliani, digitonin has the composition of C27H44O13, and it breaks up, when heated with hydrochloric acid, as follows:—
| C27H44O13 | + | 2H2O | = | C16H24O3 | + | 2C6H12O6. |
| Digitonin. | Digitogenin. | Dextrose. | ||||
—Ber., xxiii. 1555-1568.
§ 528. Digitalein is a colourless, amorphous body, easily soluble in water and in cold absolute alcohol. It may be precipitated from an alcoholic solution by the addition of much ether. It is with difficulty soluble in chloroform, and insoluble in ether. It is precipitated from a watery solution by tannin, or by basic lead acetate; saponification by dilute acids splits it up into glucose and digitaleretin. It has a sharp, acrid taste, and the watery solution froths on shaking.