1^ Scientific Intelligence, Sec. 



thus prematurely called upon to announce this substance, before ifc 

 had been subjected to a more detailed and rigid examination. Will 

 you have the goodness to publish the following remarks, as an ap- 

 pendix to my former hasty communication ? 



Solutions of the neutral salts of Treenium do not give precipitates 

 with hydrosulphuret of ammonia, if the latter be as free as possible 

 from an excess of alkali. It appears to be requisite that the oxide 

 should be previously separated by an alkali, and then the hydrosul- 

 phuret produces an abundant dark green precipitate. 



The solutions, concentrated by heat, do not afford crystals ; and, 

 if the evaporation be carried beyond a certain point, they gelatinize, 

 and in this state cannot be re-dissolved by adding more water, nor 

 indeed perfectly even by an excess of acid. An increase of heat 

 drives off the acid, appearing to effect the perfect decomposition of 

 these salts. 



The oxide obtained from these salts by alkalis is easily dissolved 

 by the stronger acids whilst in the state of hydrate : but when dried, 

 even at 212°, its solubility is greatly impaired. The alkalis will 

 dissolve a portion of the recently formed hydrate, but not sufficiently 

 so to render it an useful property in analysis. The precipitation by 

 alkalis cannot be completely performed, for, whatever care be taken 

 to attain this object, the remaining liquid will be found to contain no 

 inconsiderable quantity of the oxide. This circumstance, combined 

 with the impossibility of obtaining an unaltered solid salt (at least 

 by the ordinary means, perhaps it may be procured under the re- 

 ceiver of an air pump), renders the examination of this substance diffi- 

 cult. And the difficulty is farther increased by its saline solutions 

 not affording insoluble salts with the ordinary tests used for that 

 purpose. Triphosphate of soda only causes a slight cloudiness, not 

 much exceeding an opalescence of the liquid : which fact, however, 

 as the solution of the salt was neutral, serves to distinguish this sub- 

 stance from alumina, with which it is associated and so nearly allied. 



Oxalate of ammonia gives no precipitate in a dilute solution ; in 

 a concentrated one flocculi may be separated, but are re-dissolved 

 when washed on the filter. The carbonates afford the most satisfac- 

 tory appearance, and therefore the following experiment was made : 



Five grains bicarbonate of potassa (previously dried between bibu- 

 lous paper) were dissolved in water, and neutral nitrate of treenium, 

 added drop and drop till no farther change. A brisk effervescence 

 followed each addition of the nitrate, and an abundant yellow floccu- 

 lent precipitate was collected on a filter, and well washed. Dried at 

 212-" it weighed 0*85 grs., and its colour nearly approached that of 

 orange yellow. It effervesced in acids, and even a minute portion 

 gave a copious gelatinous salt, which, decomposed by excess of am- 

 monia, afforded a dark green precipitate, with hydrosulphuret of 

 ammonia. These properties show that the carbonate contains the 

 oxide of Treenium ; but its weight curiously coincided with the 

 quantity of alumina equivalent to 5 grs. of bi-carbonate of potassa. 



Now, half of the carbonic acid of the precipitant is equal to 1*1 

 gr., therefore it is evident that this experiment is not a case of simple 

 decomposition. The remaining liquid was therefore examined. I 



