Chemical Science, 483 



•ni4. Method of discovering Potassa by the Blow-pipe 'Ftame. — ^M. 

 Harkort of Freyberg says, that, in consequence of an observation 

 made by Kirwan, namely, that oxide of Nickel with potash, gav0 

 a blue glass before the blow-pipe, whilst soda with the same oxide 

 produced a brown glass, he was led to examine whether the dis- 

 tinction might not be made to afford a useful test. On making 

 the experiment with potash, he obtained an excellent result ; the 

 blue produced is not likely to be confounded with that produced 

 by cobalt, because it inclines to a milky appearance. So sensible 

 is this test, that the presence of potash was readily discovered in 

 the periclinite (a new variety of felspar, distinguished by Professor 

 Breithaupt,) although existing there in very small quantity. The 

 experiment relative to soda was not so successful, the glass acquir- 

 ing only a weak brown colour. — Jahr. der Chem. 1827. 



15. New Variety of Borax. — M. Payen, a manufacturer of borax, 

 observed in his vessels crystals differing from the ordinary crystals 

 of borax in hardness, and in their smaller proportion of water : 

 by examining the circumstances, he was, ultimately, able to obtain 

 this new variety at pleasure, and in any quantity. 



The new borax is in regular octoedrons j has a specific gravity 

 of 1.815 instead of 1.74 3 is harder than ordinary borax ; has a 

 bright conchoidal fracture ; does not break like common borax by 

 the sudden application of 30 or 40 degrees of heat. Ordinary 

 borax remains transparent in moist air or in water, but becomes 

 opaque in dry air ; the reverse, in both cases, takes place with 

 the new borax. It contains 30 per cent, of water j ordinary borax 

 contains 47 per cent. The crystals are very sonorous, and, unlike 

 those of common borax, are aggregated strongly together, so as 

 to cut like one solid mass. 



In soldering, the new borax will be more advantageous than 

 the old, because it swells less and flows more readily. Where the 

 borax is to be dissolved, the common kind is best, as being more 

 easily soluble. As respects, carriage, it has an advantage equal 

 weights of the two. having values as 70 and 53 ; and equal bulks 

 having values as 70 and 60. The crystalline forms and other cha- 

 racters are so distinct, that the one kind of borax can very readily 

 be distinguished from the other in commerce. — Ann. de V Industrie, 

 »• 74. 



In a second paper on the same subject, M. Payen has told us 

 how to obtain these peculiar crystals. If borax be dissolved in 

 water at the temperature of 212° Fah. in such quantity as to give 

 a solution of specific gravity 1.246 and it be then left to cool 

 slowly and regularly, small octoedral crystals begin to form at 

 the temperature of 174" F. which increase in number and size 

 until the temperature is 133°. If the mother liquor be then de- 

 canted, all the crystals left are of the kind before described : nearly 

 all the crystals formed from the mother liquor after this point 

 are borax of the ordinary sort. If the density of the boiling so- 



