176 Dr. Booth on a Theorem in Analytic Geometry. 



stinguish between quina and cinchonia, and, judging from 

 the results of my experiments, a mixture of those two salts 

 can be detected ; but chloride of lime in particular is the most 

 sensible test of the presence of cinchonia, and it therefore is 

 the reagent which should be employed, when this base is 

 mixed in small proportion with quina or any of its salts. 

 The results obtained by the use of the seven above-mentioned 

 tests fully confirm all that has been said in speaking of the 

 extraction of these alkaloids, and of their quantitative analysis 

 when mixed together. 



The sulphate of quina treated with the chloride of plati- 

 num gives a white pulverulent precipitate. The sulphate of 

 quina, treated with the same reagent, gives a curdy-white 

 precipitate. 



The sulphate of quina, treated by the red ferro-cyanide of 

 potassium, gives a precipitate which disappears in an excess 

 of the reagent ; the liquor assumes a greenish-brown colour, 

 and ammonia does not change it nor produce any precipi- 

 tate. 



The sulphate of cinchonia, submitted to the same reagent, 

 gives a precipitate less deeply coloured than the preceding; it 

 is equally soluble in an excess, but ammonia re-produces the 

 precipitate and destroys the colour in great part. 



I have likewise performed experiments with the following 

 substances, namely, bichloride of mercury, chloride of nickel 

 and cobalt, the iodide of potassium, and solution of iodine, 

 but they offer no distinctive characters. 



I will only repeat in conclusion, first, that in the preparation 

 of quina and cinchonia, lime should be replaced by soda: 

 carbonate of potash or soda may be employed, but they have 

 the inconvenience of dissolving part of the cinchonia ; se- 

 condly, that in case of a quantitative analysis being under- 

 taken, the same alkali alone should be employed to precipitate 

 those bodies ; and thirdly, that in case of sulphate of quina 

 being supposed to be adulterated with the sulphate of cincho- 

 nia, and that it may be wished to ascertain the extent of adul- 

 teration, the tests upon which reliance can be placed, are, first, 

 chloride of lime ; secondly, chloride of calcium; thirdly, lime- 

 water; and fourthly, ammonia and carbonate of ammonia. 



XXIX. On a Theorem in Analytic Geometry. By James 

 Booth, Esq., LL.D., M.R.I.A* 



IT has been justly remarked by an author who has himself 

 largely contributed to the advance of mathematical science, 

 * Communicated by the Author. 



