424 Scientific Intelligence. 



tate, and evaporating; the acetyl being thus displaced by fluorine^ 

 The substance is obtained in the form of needle shaped crystals,, 

 often a millimeter in diameter and a centimeter long, grouped 

 radially and probably monoclinic, analogous to the fluostannate of 

 Marignac. It is permanent in dry air, but turns brown in moist 

 air, being decomposed by water so as to yield hydrated lead 

 peroxide, hydrogen potassium fluoride, and hydrogen fluoride. 

 Heated to 100°-1 10° for some hours the mass remains constant; 

 but at 200° hydrogen fluoride is evolved, and at higher temper- 

 atures, but much below a red heat, a gas is set free having the 

 characteristic odor of fluorine, and liberating iodine in large 

 quantity from iodide of starch paper. Small crystals of silicon 

 placed in the open end of the evolution tube burn with vivid 

 incandescence, sometimes with explosive violence, in the issuing 

 gas. There can be no doubt that this gas is really fluorine. If 

 the potassium fluorplumbate loses only its hydrogen fluoride at 

 230°, with traces only of fluorine, one gram should give 47 cc of 

 fluorine; the admixed hydrogen fluoride being removed by pass- 

 ing the gas over potassium fluoride. If the sodium salt now 

 under investigation proves to be (NaF) 2 PbF 4 it would yield 

 fluorine pure at once. The author also describes the preparation 

 of fluorplumbic acid and lead tetrafluoride. — J. Cheni. Soc, lxv r 

 393-402, June, 1894. G. f. b. 



5. On the Structure of the Flame of Cyanogen. — The structure 

 of the flame of burning cyanogen has been studied by Smithells 

 and Dent according to the method proposed by the first named 

 chemist in connection with Ingle. The cyanogen was prepared 

 by heating mercuric cyanide and was collected over mercury. 

 When burned in the cone-sej>arating apparatus, the flame at the 

 top of the outer tube consists of two parts, an inner cone-shaped 

 region having a bright peach blossom tint, and an outer or 

 enveloping cone, shading off from a bright blue to a greenish- 

 grey. As air is gradually added the inner cone becomes smaller 

 and soon enters and descends the outer tube, being surrounded 

 by a rosy halo, which disappears and is replaced by a blue one 

 as the amount of air increases. The outer cone retains its place 

 at the top of the outer tube and remains of the same color. 

 More air still, extinguishes the outer cone and causes the inner 

 one to become bluer and its halo greener. Examination of the 

 interconal gases showed the presence of carbon dioxide and 

 monoxide, cyanogen, nitrogen, nitrogen dioxide and tetroxide. 

 Analysis gave CO 25-4, C0 2 0-8, (CN) 2 6-1, N 2 66'9, NO 0-3, 

 N0 2 0-4, when the proportion of air to cyanogen was 3*52 : 1. 

 From their results the authors conclude : (1) that the cones may 

 separate when the ratio of air to cyanogen is 3*3 : 1 ; (2) that 

 when cyanogen is burning with the minimum quantity of air, 

 carbon monoxide is practically the only oxidation product ; 

 (3) that as the air supply increases the quantity of carbon di- 

 oxide increases, until it equals one half the volume of the mon- 

 oxide; (4) that cyanogen is present in the interconal gases 



