X • The INTRODUCE 1 0 N. 
XIII. That a Load-ftone will take op much more Iron, when armed or capped, than.it can alone j 
and that tho’ the Iron-key, or Ring, be fufpended by the Load-hone, yet the magnetical Particles do 
not hinder the Ring or Key, from turning round any Way either to the Right or Left. 
XIV. That the Force of a Load-ftone may be varioufiy encreafed or leffened, by the various- Ap- 
plication cif. Iroii,. or another Load-ftone to it. 
XV. That a ftrong Magnet, at the leaft Diftance from a leffer or a weaker, cannot draw to it 
a Piece of Iron adhering to fuch leffer or weaker Stone ; but if it comes to touch it, it can draw it 
from the other 5 but a weaker Magnet, or even a little Piece of Iron, can draw away, or feparate 
a Piece of Iron contiguous to a greater or a ftronger Load-ftone. 
XVI. That in our North Parts of the World, the South-Pole of a Load-ftone will raife up more 
Iron than the North-Pole. 
XVIL That a Plate of Iron only, but no other Body interpofed, can impede the Operation of the 
Load-ftone, either as to its Attraction, or directive Quality. Mr. Boyle found it true by Glaffes 
fealed hermetically ; and Glafs is a Body as impervious as moft are to any Effluvia. 
XVIII, That the Power, or Virtue of a Load-ftone, may be impaired by lying long in a wrong 
Pofture, as alfo by Ruff, Wet, &c. and may be quite deftroyed by Fire. 
Experiments on the Load-ftone, by the Honourable Robert Boyle, Efq-> in his own Words. 
I. Mr. Boyle found that by heating a Magnet red-hot, it could be fpeedily deprived of its attractive 
Quality. 
II. If a Lqad-ftonebe heated red-hot, and then cooled, either with its South-Pole to the North, in 
a horizontal Pofition, or with its South-Pole downwards in a perpendicular one, it will change its 
Polarity, the South-Pole becoming the Nothern, and vice ver/a. 
III. By applying the Poles of a very fmall Fragment of a Load-ftone to the oppofite vigorous 
ones of a good large Magnet, Mr. Boyle found he could fpeedily change the Poles of the Fragment, 
but he could not effeeft it in a Fragment that was conftderably bigger, tho’ he tried many Hours, 
IV. He obferved, that well-tempered and hardened Iron-Tools, when heated by Attraction, turn- 
ing, filing, &c, they would, while warm, attraeft the Filings or Chips of Iron and Steel, but not 
when cold ; yet, fays Mr. Moxon , I remember once to have feen myfelf, and tried, that a Piece of a 
File, which was in the Hands of Mr. Harwell, the SpeCtacle-Maker, did retain fuch attractive Qua- 
lity, that it would take up and keep fufpended the Key of a Cabinet, or Efcrutore, and needed no Fric- 
tion to excite this magnetical Virtue. 
V. The Iron-bars of Windows, which have long flood in an ereCt Pofition, do grow permanently 
magnetical, the lower Ends of fuch Bars being the North-Poles, and the upper the Southern ; for, 
according to the Laws of Magnetifm, we find the lower Ends of fuch Bars will drive away the 
North-End of fuch a Needle, and will attraCt the Southern ; which fhews, that by a continual" Paf- 
fage of the fubtile magnetical Particles through them, they are turned into a kind of Magnet them- 
Lives. 
VI. If a Bar of Iron that hath not long flood in an ereCted Pofture, be only held perpendicularly, 
its lower End will be the North-Pole, and attraCl the South-Point of a touched Needle ; but then 
this Virtue is tranfient, and will fhift as you invert the Bar ; for the other End, when held lowermoft, 
will prefently become the North-Pole : Wherefore, in order to render the Quality of Verticity per- 
manent in an Iron-bar, it mu ft remain a long while in a proper Pofition : But the Fire will pro- 
duce this EffeCl in a very fhort Time; for as it will immediately deprive a Load-ftone of attractive 
Power, or change its Poles (as in Experiment i, 2 ,) fo it will as foon give a Verticity to a Bar of 
Iron, it being heated red-hot, and cooled in an ereCt Pofition direCtly North and South ; nay, it hath 
been obferved often, that even Tongs and Pokers, by being often heated, and then let to cool in a 
Pofition near to ereCt, have gained this magnetical Property. The Reafon of which very different 
Effects of the Fire on a Magnet and on Iron Mr. Boyle , with his ufual Modefty, fuggefts to be 
this, That the peculiar Texture of Conftitution, by which a Magnet differs from common Iron, one 
being accurate and fine, the other rough is fpoiled by the rude and violent Attacks of the Fire. But 
this mighty Agent, by working upon Iron, foftens and opens the Pores of the Metal (which is harder 
than Iron-Oar •) fo that it becomes capable of being pervaded by the magnetical Particles, and by 
that Means gains a vertical Quality. 
VIL Mr. hoyle found, that, by heating of E'rglijh Oker red-hot, and placing it to cool in a proper 
Pofture, it plainly gained a magnetic Power. 
VIII. The fame Noble Gentleman found that an excellent Load-ftone of his own, having lain al- 
moft a Year in an inconvenient Pofture, had its Virtues fo impaired, that he, at firft, thought that 
fomebody had fpoiled it by Fire. 
IX; If a Needle be well touched on a good Load-Stone, ’tis known it will, when duly poifed, 
point North and South ; but if it bath one contrary Touch on the fame Stone, it will immediately 
be deprived of that Faculty ; and by another Touch it will have its Poles quite changed ; fo that the 
End which before pointed North, {hall now point Southward, 
X. Dr. Power , and Mr. Boyle , both found that after a red-het Iron had gained a Verticity by be- 
ing well heated and cooled North and South; and then alfo hammered at the Ends, the Virtues would 
immediately be deftroyed by two or three... Blows of a ftrong Hammer fmartly given about the Mid- 
dle of it. 
XL Mr. Boyle found, that by drawing the Back of a Knife, or long Piece of Steel-Wire, LM 
the Pole of a Load-ftone leiiurely once, or divers Times, beginning the Motion from the Equa- 
V ' . " ' ' ’ tor , 
over 
