Cleaveland on Mineralogy and Geology. 391 
Ferroprussic acid, the ferrocyanic acid of the French chemists, has 
proved, hitherto, a stumbling-block tofme, in reducing the results of my 
experiments to the atomic theory. I have subjected it to very numerous 
trials in many states of combination, and have sought, with great pains, 
to accommodate the results to the doctrine of prime equivalents, but hi- 
therto without success. The following facts, however, may, perhaps, be 
deemed of some consequence. 
In the first place, the prime equivalent of the erystallized ferroprussiate 
of potash is 13.125, compared to oxide of lead 14, and to nitrate of the 
same metal 20.75 ; that is, 13.125 of the former salt neutralize 20.75 of the 
latter. In the second place, 14 parts of oxide of lead yield 21 parts of dry 
ferroprussiate of lead ; or the atomic weight of dry ferroprussic acid is 7. 
The mean of my analyses of ferroprussiate of lead, gives the relation of 
the constituents of the acid, as marked in the table. These proportions, 
reduced to the atomic weight 7, afford 
Carbon . e 2 - = 2.5774 
Azote. ; 2 3 3 é 2.4703 
Ferreous matte : : Z ; : 1.9523 
7.0000 
Were we to suppose the prime equivalent of the ferroprussic acid 7.5, 
instead of 7 ; and were we farther to suppose that the carbon in the above 
result should be 2.25 = 3.atoms, and the azote = 3.5, or 2 atoms, then we 
might conceive an atom of dry ferroprussic acid to be made up of 
Carbon : 3 A : 3 3 atoms 2.25 
Azote = = ~ - + 2 — 3.50 
Iron .. = * - . 2 1 ~—— 175 
7.50 
But experiment does not permit me to adopt this theoretical represen- 
tation. ‘ 
The best mode that has occurred to me foranalyzing ferroprussiate of 
potash, is to convert it, by the equivalent quantity of nitrate of lead, into 
the ferroprussiate of this metal; ilen to separate the nitrate of potash by 
filtration; and, after evaporation, to determine its weight. In this way, 
13.125 grs. of crystallized ferroprussiate of potash afford 12.33 grs. of nitre, 
which contain 5.8 of potash*. By heating nitric acid in excess on 21 grs. 
of ferroprussiate of lead, I obtained 2.625 grs. of peroxide of iron, equiva~ 
lent to 1.8375 of the metal. Hence 1 infer, that the iron in the ferroprus- 
siate oflead is in the metallic state ; for the joint weights of the carbon 
and azote contained in 7 grains of the dry acid is 5.0477 ; and the differ- 
ence, 1.9523, approaches too closely to the above quantity, 1.8375, for us 
to suppose the metal to be in the state of protoxide. In fact, 2.625 parts 
of peroxide X 0.9 = 2.3625 of protoxide, is a quantity much beyond what 
experiment shows, to be present. 
eee ee ee ee eee 
Ill. An elementary Treatise on Mineralogy and Geology, designed 
for the use of Pupils, for Persons attending Lectures on these 
Subjects, and as a Companion for Travellers in the United 
States of America. Illustrated by Six Plates. By Parker 
Cleaveland, Prof. of Mathematics, §e. in Bowdoin Col. 2d. 
edit. 2vols. 8vo., pp. 818. Boston—Cummings & Hilliard. 
Wuutsr science extends her empire in all directions over Eu- 
rope, she is not unmindful of the Western world, but is rapidly 
establishing a new throne on the vast continent of North Ame- 
rica, and where, till within a comparatively short period, wilds 
* By careful desiccation 1.69 grains of water may be separated from 
13.125 grains of the salt. 
