Increasing the Stability of Quinidine. By H. O. Madan. 247 



energy. After a time, however, the temperature of the now colloidal 

 sulphur rises at approximately the same rate as at first. 



(b) That, when the conditions are reversed, and a mass of plastic 

 sulphur at a temperature of, say, 200° C. is allowed to cool steadily, 

 the temperature at first falls at a uniform rate ; but at a point near 

 155° it almost ceases to fall for a time, the evolution of the stored-up 

 statical energy being sufficient to maintain the temperature (as if by 

 an internal furnace), in spite of the continued emission of heat from 

 the cooling mass. After a time the temperature recommences to fall 

 in accordance with the usual law of cooling. 



Now it seemed likely that something of the same kind might 

 occur in the case of quinidine, and that prolonged heating might be 

 necessary to effect the complete conversion of the crystalline into the 

 colloidal form. 



To investigate this point, some quinidine in crystals was placed in 

 a beaker and heated in an oil-bath maintained at a steady tempera- 

 ture of 186°-1S8° C. As soon as it was thoroughly melted and the 

 liquid had attained the temperature of the bath, a portion was poured 

 off and allowed to cool on a slip of glass. This portion was labelled 

 " A." The remainder in the beaker was kept at a steady temperature 

 of 186° (approximately) for half an hour, at the end of which time 

 some of it was poured off upon a slip of glass and labelled " B." The 

 rest was kept at the same temperature of 186° for a further half hour 

 (making the whole period of heating one hour), and then poured 

 upon a slip of glass and labelled " C." 



These experiments were made on March 10, 1900, and the 

 specimens were preserved in a tray under a bell-jar and examined at 

 intervals. 



The results up to the present date are as follows : — 



March 29, 1900. — Specimen A showed already signs of crystal- 

 lisation when examined under the Microscope. Specimens B and C, 

 which were dark red in colour, showed no signs of any change, and 

 were quite transparent. 



March 12, 1901. — Specimen A had become quite opaque and 

 crystalline. Specimen B was still transparent and unaltered. When 

 a little of it was heated on a slip of glass, it remained unchanged up 

 to the melting point, but then tufts of crystals began to appear in it. 

 Specimen C was quite unchanged ; it was dark red and transparent. 

 When a portion of it was heated upon a slip of glass, it did not turn 

 opaque and crystalline either before fusion or when it became liquid. 

 It was allowed to cool, and then re-heated ; and this cooling and re- 

 heating was repeated three or four times, but no sign of crystallisation 

 appeared, and no crystals were visible under the Microscope. The 

 substance, in fact, behaved like a permanent resin, though it never 

 became quite so fluid, when melted, as the other specimens. 



The inference which we seem entitled to draw from the above and 

 other corroborative experiments is the following : — That in order to 



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