6 
tp:rrestrial magnetism— atmospheric electricity. 
dore masses of Como. Wack6 is a rock 
formed by the action of water upon these 
rocks, and contains calcareous spar, zeolites 
and piperine, 
'I'here is reason to think that the crystals 
which are found in bay-salts, have been de- 
posited after the consolidation of the rocks in 
which they are found, because most of them 
are altered by a strong heat, and lose their 
water of crystalization. Fournet attributes 
the formation of zeolites to the transportation 
of the elements by water from the neighbour- 
ing rocks. 
ORGANIC matter. -T he mode in 
which organic matter undergoes decomposition 
has not been much studied, but a few curious 
facts have been ascertained. Davy found 
the manucripts of Herculaneum converted 
into a kind of turf, the leaves being united into 
a single mass by a peculiar substance, for- 
med by the chemical changes of the vege- 
table matter. 'J'he guano in Peru is found in 
deposites of 50 or 60 feet deep, and is formed 
of the excrement of herons which inhabit the 
coast. 
Necker de Saussure has observed the teeth 
of the ursiisspiloeus in the mines of Carmiola, 
corroded as if by an acid. Turpin has no- 
ticed the egg of the garden snail to be cover- 
ed on the interior surface of its envelope, 
with rhombohedral crystals of carbonate of 
lime. The cellular tissueof the cactus, and 
the medullary tisue of palms contain oxalate 
of lime in crystals. 
NITRIFICATION— When distilled 
water is placed over plates of iron, lead, zinc, 
or tin, ammonia is formed in consequence of 
the combination of the hydrogen of the water 
with the azote of the air. 
Vasquelin found ammonia in some rusty 
spots on a sabre, which had been employed 
by an assassin, and that other traces present- 
ed the same substance. Protoxide of iron, 
zenite, earthy oxide of iron heated in a tube, 
give out ammonia was detected in the ferru- 
ginous water of Passy after evaporation. 
Boussingault has observed it likewise in oxi- 
dized iron by taking a fragment of it, treating 
it with dilute muriatic acid, evaporating the 
washings, and heating the residue with quick- 
lime in a tube, using the precaution to mois- 
ten them with water. Faraday obtained am- 
monia, by heating zinc foil in a glass tube 
with potash. The experiment succeeded 
even in hydrogen gas. Potassium, iron, tin, 
lead, and arsenic likewise afford much of it, 
with soda, lime, barytes or potash. The 
alkalines alone do not yield it. 
The formation of saltpetre has long been a 
subject of interest. Dumas conceives that 
the presence of organic matter is not essen- 
tial. Claubry attributes its production to the 
action of an acid moisture upon carbonate of 
lime. 
Fournet thinks that nitric acid may be form- 
ed without the presence of organic matter, by 
the re-action alone of the elements of air and 
vapour of water. For according to Saussure, 
oxygen is more condensable by porous bodies 
than azote, in the proportion of 6'5 to 4 00 ; 
and Gay Lussac and Humboldt have ob- 
served that air disengaged from water by 
boiling, contains more oxygen in proportion 
to the slowness of its extrication. The result 
is that oxygen is not only retained with a 
greater power, but the composition of the 
last portions of the air approaches pretoxide 
of azote. Fournet has concluded, that the 
united action of porous bodies and of water 
upon the elements of air, would produce at 
first, protoxide of azote; then nitrate of am- 
monia, which when decomposed, resolves 
itself into protoxide of azote and vapour of 
water. The nitrate acts upon the alkaline 
carbonates and forms nitrate of potash, while 
the ammonia is disengaged in union with car- 
bonic acid. He applies his theory to explain 
the production of nitrate of ammonia, dis- 
solved in rain by the electric agency. He 
concludes by observing, that in every electric 
chemical action, however feeble it may be, if 
water is decomposed in contact with air, 
ammonia is formed. 
LASTGEOLOGICAL REVOLUTION. 
— Becquerel endeavours to calculate this pe- 
riod, by a method which it must be allowed is 
extremely vague. He finds that the cathedral 
of Limoges, which has stood for four centuries, 
and is built of granite, is decomposed on that 
side where the winds and the rain beat to the 
depth of 82 lines, and that the rock in situ is 
disintegrated to the depth of 5 feet or 720 
lines. If both have progressed at the same 
rate, he conceives that the rock in its natural 
place must have been decomposing for above 
82 000 years. 
TERRESTRIAL MAGNETISM.-- 
From the facts which have been brought for- 
ward by Humboldt and others, it appears pro- 
per, that experiments should be made upon 
the magnetism of the rocks, which constitute 
the formations of the country in which the 
experimenter is placed, or at least to deter- 
mine at what point the extent of oscillations 
diminishes without changing their number. 
A TM O S P H ERIC ELECT RIC Ff Y.— 
Saussure has shewn that in summer the elec- 
tricity of the calm air is much weaker than 
in winter; and that the apparent force of 
electricity, depends not so much on the ab- 
solute height of the place of observation as 
upon the relative height, or on the insulation 
of tlie place. Disseminated as this principle 
is through the medium of the vapour of water, 
it is highly probable that it exercises tio in- 
considerable effect on the plants and animals 
which are of necessity subjected to its influ- 
ence. 
Becquerel terminates the first volume of his 
work, with some remarks upon the agencies 
by which the decomposition of some rocks and 
the formation of some insoluble compounds 
may be explained, which comprehends a re- 
capitulation of some points. But he shews 
more particularly, how electro-chemical ac- 
tion operates in producing many minerals. 
Phosphate of iron in mines and crevices he 
considers to be the result of the action of 
electricity, which is disengaged during the 
peroxidation of iron and the decomposition of 
organic matter. The formation of the chro- 
mate of lead as it exists native, may be imi- 
tated by treating a solution of nitrate of lead 
with chalk and then with chromate of potash. 
In the course of a month or two, crystals of 
