1824.] Scientific Intelligence. 395 



certain lapse of time.' It is with much diffidence that I am compelled 

 to differ from the high authority of the President upon this interesting 

 point : but there is one observation which I made, which, I think, 

 nearly disproves the supposition. All fluids, which are known to ab- 

 sorb air into their pores, invariably emit it when the pressure of the 

 atmosphere is removed : but upon an attentive examination of large 

 bodies of mercury, variously heated in the vacuum of an air-pump, I 

 never saw a bubble of air given off from the surface of the metal. Air 

 will rise from the contact of the mercury with the glass in which it is 

 contained, in exact inverse proportion to the care with which it has 

 been filled, but it never rises from the surface of the mercury alone. 

 The difficulty of properly filling a barometer tube, I attribute to the 

 attraction between the glass and the air, not to that between the mer- 

 cury and air ; and I believe that air will insinuate itself a little way 

 between the glass and the metal, at the exposed end of a boiled tube, 

 but that this cannot happen if the end be plunged in mercury ; and, 

 consequently, that no deterioration of barometers is to be apprehend- 

 ed from this cause. Such a deterioration, indeed, if it had existed, 

 must, long ago, have been detected from the instruments themselves ; 

 for although the register of the Royal Society is not in such a state as 

 to enable any one to reason upon its conclusions, that of the Royal 

 Observatory of Paris, and some others, must have disclosed the fact." 



VI. Connexion of Phosphorescence with Electricity. 



The sulphate of quina was shown by M. Callaud d'Annecy some 

 time since to become highly phosphorescent when rubbed at a tempe- 

 rature of 212°. MM. Dumas and Pelletier have ascertained that it 

 becomes highly negatively electrical when rubbed on woollen cloth, 

 and hence were led to the verification of a suspicion they had long 

 entertained that phosphorescence was an electrical phenomenon. 

 About two or three ounces of sulphate of quina were introduced into 

 a glass flask, and heated for half an hour in a water bath at 212 # F., 

 it then by friction gave out a sufficiently intense light. The flask was 

 closed by a cork, through which passed a wire pointed at the inner 

 extremity, and terminated by a ball at the external end; on approach- 

 ing this ball, two or three times to the knob of a voltaic electrometer 

 furnished with its condenser, having taken care to shake the flask 

 before each contact, the leaves became so electrical as to diverge as 

 much as the instrument would admit of, the electricity being con- 

 stantly positive. 



The sulphate of cinchonia, which is phosphorescent like the sul- 

 phate of quina, though less so, also became electrical in the same 

 manner. Its electricity, though of the same kind, was not so strong as 

 that of the preparation of quina. — (Ann. de China, xxiv. 171.) 



VII. Preparation of Oxide of Nickel. By M. Bcrthier. 



Speiss, or impure nickel, is to be reduced to fine powder and roasted 

 till it gives off no further vapours of arsenic, the heat being at first 

 moderate to prevent fusion, and then increased. Metallic iron. in the 

 state of filings or nails is to be added in a quantity which ought pre- 

 viously to be determined, and the whole dissolved in boiling nitro-mu- 

 riatic acid, so much nitric acid being used that no protoxide of 

 iron remain in the solution ; evaporate to dryness and re-dissolve in 



