1824.] 



Spirit of Philosophical Discovery. 



The gilding of Jhtterl and carved pic- 

 ture-J'rames has l)cen foiiiul lo depend, 

 in one of its most difiioult operations, 

 that of lajinn; on the leaf-gold, upon 

 cjpclric action. After the frames are 

 •Inly prepared, by a com|)Osition wliicli 

 is laid upon liicm with a brush, and tlie 

 same has becoiiic dry, the surfaces in- 

 tended to be gilt are brushed over wilh 

 spirits of wine. The gold leaf, in suit- 

 lible-sized pieces, is then taken up on a 

 flat camei-!)air brush, and presented 

 within half or three-quarters of an iucli 

 of the part it is intended to cover, when 

 instantly the gold-leaf flies off from tlic 

 biusli, and applies itself to every part of 

 lite moistened conipositirm which it is 

 capable from its size to cover, and covers 

 the same, however irregular in shape, 

 more perfectly than could otherwise be 

 efi'ected. The evaporating of the spirit 

 excites the electric action which is tlie 

 cause of this effect, which it is no less 

 pleasant to witness than useful to 

 obtain. 



Tlie spontaneous combustion of dung- 

 hills, when suffered lo become dry, will 

 Sometimes happen, as has been ascer- 

 tained and attested by Dr. Svmuel 

 Rockwell, o;i the farm of Mr. Ciiarles 

 Elliot, at Sharon, in Connecticut State, 

 in America. The dung of the stable 

 liad lieen flimg out of a window, and 

 accnnuilated in a heap, in a back-yard 

 lilllc frequented ; but from which sparks 

 of fire having been observed lo blow by 

 some of the family, an alarm was in- 

 stantly given, and the neighbours called 

 in, who made a careful search and tho- 

 rough removal of the top of the dung- 

 heap which was on lire, whereby they 

 clearly ascertained, that a spontaneous 

 coml)ustion of the almost dry and fer- 

 nienling mass had occasioned the peril 

 of the whole farm premises, and not llie 

 diabolical act of an incendiary, as was 

 at first naturally supposed. — Silliman's 

 Journal, No. 11. 



The causes of tornadoes, hurricatics, 

 and squalls, have been thus assigned by 

 Dr. Ware, of Philadelphia. The air 

 being a perfectly clastic fluid, its density 

 is Jepeudcnt on pressure, as well as on 

 Leat, and it docs not follow that air, 

 which may be heated in conse(|uence of 

 its proximity to the earth, will give 

 place to coUler air from above. 'J'lio 

 jircssuro of (he atmosphere varying with 

 the elevation, otio stratum of air may be 

 as much rarer by the dimiimlion of 

 prcssnro consequent to its altitude, as 

 «lenser by the cold cons<<|uont to its 



Monthly Mag. No. 397. 



551 



remoteness from the earth, and another 

 may be as much denser by the increased 

 |)ressine arising from its proximity to 

 the earth, as rarer by being warmer. 

 Hence, when unequally healed, dilTerent 

 strata of the atmospliore do not always 

 disturb each other. Yet, after a time, 

 the rarefaction in the lower stratum, by 

 greater heat, may so far exceed that in 

 the upper stratum, attendant on an in- 

 ferior degree of pressure, that this stra- 

 tum may i)reponderate, and begin to 

 descend : whenever such a movement 

 commences, it must proceed with in- 

 creasing velocity ; for the pressure on 

 tiie upper stratum, and of coinsc its 

 density and weight, increases as it falls; 

 whilst, on the contrary, tiie density an(i 

 wei^i^hl of Ihe lower stratum must lessen 

 it as it rises, and hence the change is at 

 times so much accelerated, as to occa- 

 sion the furious and suddenly varying 

 currents of air which attend toruailoes, 

 hurricanes, and squalls. — SiUi>nau's 

 Journal, No. 12. 



Riibii-poiiited guld pnns liave been in- 

 troduced, lo obxiate the r:ij)(d wear of 

 steel pens on (he paper, and thedeslruc- 

 tive corrosion of them by the ink : the 

 ruby points or nibs are set in fine gold, 

 not fashioned eylindiical like a qiiilj, but 

 ill two separate plates, meeting in an 

 angle like a Irougii : the spring of these 

 gold plates occasions the slit to open 

 and shut, freely and perfectly, accord- 

 ingly as greater or less pressure on the 

 jiaper is applied, so that the same pen 

 will either write a bold text hanil, or 

 form priuling letters, or write a delicate 

 small hand, accordingly as it is used ; 

 and they are exceedingly durable. Steel 

 nibs, filling on to quill pens, are found 

 to answer well, except as to their wc<ir 

 and corrosion. 



Natural Snow-balls. — In Morris Coun- 

 ty, in New Jersey, United States, in 

 January 1809, the Rev. D. A. Clauk 

 observed, whilst snow was lying on Ihe 

 ground, that a shower of rain fell, and 

 froze almost instantly and smoothly on 

 tiie top of the snow ; and, quickly after- 

 wards, another fall of snow occurred : 

 soon alter which, the wind happening to 

 blow strongly, it set this ujiper snow 

 very generally in motion, producing in- 

 numerable balls, or short cylinders ra- 

 ther,whieh, on slopinggrounds, acquired 

 in many instances the size aiul round- 

 ness of barrels, before they either rested 

 through their own accumulaled weight, 

 or were slopped by the fences, banks, 

 or oilier iiie<jtialitiesof the ground. 



•1 Ji The 



