recognizing the Non-volatile Alkalies and Alkaline Earths. 331 

 ever been a difficulty in distinguishing it when small quantities 

 are present. Here I may add that this method is particularly 

 adapted to the discovery of small quantities of strontia ; and also, 

 when the substances of this group occur m so small quantities 

 that they are no longer recognizable in the wet way : by the re- 

 actions of the flame and coloured medium they are readily distin- 

 guishable. . , ,. 



The characteristic colours which baryta, strontia, and lime 

 communicate to the flame, are best observed when their sulphates 

 are exposed on the point of a piece of the finest platinum wire 

 to the outer part of an air-flame. And further during the 

 burning, the colours they produce can be increased m intensity 

 bv first putting them into the reducing flame, and then either 

 moistening them with hydrochloric acid, or by holdmg some 

 asbestos moistened with this acid in the flame directly under the 

 point of the platinum wire on which the substances are supported. 

 In commencing the experiments with this group, in order to 

 ascertain how far these characteristic colours would serve to di- 

 stinguish the members of it, I observed that in all proportions 

 as far as they are capable of being recognized m the presence ot 

 each other, they always burn away in the following order :— iirst 

 is seen the green of baryta, next the bright red of strontia, and 

 la^^tly the dull and scarcely visible red of lime. ^^ hen, however, 

 a large quantity of strontia or lime is present m proportion to 

 the baryta, the red colours of the two former are observed at 

 the same time ; and in this case the green of baryta can only be 

 seen distinctly by passing the wire on which the substance is 

 supported in and out of the flame during the observation. Un 

 continuing these experiments, I found also that when much 

 lime was present it modified considerably the colours of baryta 

 and strontia; so much so, that these two last, when m small 

 proportions, could not be distinguished. I tried further the 

 effect of looking through coloured media, as in the case ot the 

 alkalies, but could find none that were altogether satisfactory. 

 By a solution of indigo more dilute than that used for the alka- 

 lies, strontia can be distinguished from lime, as through it lime 

 appears olive-green, and strontia intense red, when they are first 

 introduced into the flame after being moistened with HLl. As 

 it is easy to separate the baryta and almost all the strontia irofti 

 the lime by means of dilute sulphuric acid, and as when only 

 baryta and strontia occur together they arc easily distinguished 

 by the naked eye, when one part of baryta occurs with one hun- 

 dred parts of strontia, and vice versa, I found it best to separate 

 baryta and strontia together from the lime. 



The following method answers peifcctly for their separation. 

 The carbonates as usually obtained are dissolved in hydrochloric 



