GLEANINGS IN SCIENCE. 
7 
prosed to heat along with quartzose sand. The iron, I found, was borne up along with 
the salt fumes. The sandstone, formed in this way, was deeply stained with iron, 
and other most curious appearances presented themselves. 
Every one who has seen a sandstone quarry, must have noticed evident traces of 
iron, the rock being stained in a great variety of ways ; sometimes in parallel 
layers,— sometimes in concentric circles, or rather in portions of concentric spheres, 
like the coats of an onion,— and, generally speaking, disposed in a way not account- 
able by deposition from water. All these appearances I would account for, by sup- 
posing the rock, either at the moment of its agglutination into sandstone, or at 
some subsequent period, to have been penetrated by the fumes of salt, charged with 
iron, also in a state of vapour. 
I may mention one very curious result of my experiments with salt and iron, act- 
ing upon sand, namely, that, upon breaking up the specimen of artificial sandstone, 
an appearance often presents itself of incipient crystallisation, if I may use this 
term ; a number of large, shining, parallel faces pervade the whole mass, and, by 
holding the specimen at the proper angle to the light, this appearance becomes very 
obvious. What the nature of these crystals is, I have not investigated ; but as they 
very much resemble what we see in different kinds of sandstone, I am of opinion 
that they hold out a fair expectation of our being able to produce many of the 
crystalline appearances with which we are familiar in nature. 
Common sea-salt, such as I have used, as is well known, is not pure muriate of 
soda : and, in my experiments, I have mixed various other substances with it. In 
Nature, we must suppose that various contaminating substances would in like man- 
ner occur, to diversify the phenomena ; and, accordingly, we do find a boundless 
variety, in the aspect not only of sandstone, but of almost every kind of, rock ; and 
I am by no means without expectation, that, in the course of time, we shall be able 
to imitate in our laboratory as many of these varieties as we choose to exhibit, 
1 have long been engaged also in a series of experiments on the formation of 
Crystallites, the name by which, as I have before stated, every crystallised rock 
might, perhaps, be usefully distinguished in contradistinction to Aggregates, or those 
formed of fragments. This great object in experimental geology., I hope to accom- 
plish by means of an instrument which I have long had in use, for the regulation 
of high heats, a description of which may probably soon be laid before the Society, 
together with some further results in support of the Huttonian Theory' of the Earth. 
II. An Account of Professor Carxini’s Pendulum Experiments on 
Mont Cenis. 
[From the Quarterly Journal of Science and Arts,Vol . II. No. 8.] 
We believe that no account of Professor Carlini’s pendulum experiments on 
Mont Cenis, has hitherto appeared in the periodical scientific publications of this 
country: the experiments are, however, , well deserving of such notice, having 
been conducted with great care, and having had a specific object in view, which 
object seems to have been satisfactorily accomplished. The following brief account 
of them, taken from the original memoir published in the Appendix to the 
44 Ephemeride di Milano” for 1824, may not be unacceptable to those of our read- 
ers who interest themselves in subjects of this class. 
The length of the simple pendulum vibrating seconds, is a measure of the inten- 
sity of gravitation; i. e. of the excess of the force of gravity over the centrifugal 
force. In consequence of the ellipticity of the earth, and of the difference in the 
direction of the two forces, the intensity of gravitation varies according to the dif- 
ferent latitudes. It also varies, in the same latitude, according to the greater or less 
elevation of the pendulum above the level of the sea ; i. e. according to its greater 
or less distance from the centre of the attracting force. 
Had the earth a perfectly level surface, such, for instance, as it would have if ifc 
were everywhere covered by a fluid, the force of gravity, in receding from the 
surface, would diminish in the duplicate proportion of the distance fron the earth’s 
centre. In the actual state of the globe, however, its continents and its islands 
are raised above the general level of the sea, by which it is only partially covered ; 
and if a pendulum be raised, on the surface of the land, to a known elevation above 
the sea, the diminution of gravity will not be, as in the more simple case, propor- 
tioned to the squares of the respective distances from the earth’s centre ; but that 
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