4 Chemistry and Physics. 125 
‘: 2. Silica once precipitated in any way, does not redissolve in acid. 
Be 3. Weak acids decompose alkaline silicates at common tempera 
a tures, the silica appearing as jelly or in gelatinous flocculi. 
_ 4. Finely divided hydrous or anhydrous silica decomposes the solu- 
we tions of alkaline carbonates and dissolves in them, at a boiling heat. 
be 5. Silica at common temperatures from an alkaline silicate or fluorid 
a of silicium, is a definite hydrate HO SiO; heated to 212°, it becomes 
3 HO 2810,. 
. 2 6. Metallic solutions precipitate from an alkaline silicate a mixture of 
hydrate of silica and a metallic silicate; the latter alone dissolves in the 
mineral acid. 
7. A clear and very strong solution of silica in hydrochloric acid is 
a obtained by dissolving silicate of copper in the acid and precipitating 
a the copper by sulphuretted hydrogen. 
8. The last named solution evaporated under the air-pump gives the 
hydrate HO SiO, in perfect crystals, which are small transparent 
edles in stars or tufts. »U. 8. 
~ 17. On the Inorganic ‘Substances in the different parts of Plants ; 
by Dr. C. Rammetssere, (Poggendortf’s Annalen.)—The examina- 
e quantity of phosphoric acid in seeds has 
fa, gad G. C.S. 
A esia, in proportions to form spinel, were mixed 
with fused boracic and ont ait r cent. bichromate of potash. 
‘Xposed on platina foil to the highest temperature of the porcelain fur- 
nace of Séyres, a product was obtained ; the surface and interior cavi- 
ties of which were covered with crystalline facets having the form of 
the reguls hedron; rose red, transparent and readily scratching 
quartz. They were completely infusible by the blowpipe—and there 
can be no doubt of their identity with spinel. i 
A substitution of protoxyd of manganese for the magnesia produced 
farge lamine, having the form of equilateral triang'es “ oe hexa- 
gons. These parently manganesian spinel, whic S never 
TDineinendio te ninant kingdom. Oxyd of cobalt substituted 
for magnesia, gave blue-black regu 
. 
