Chemistry and Physics. 73 
? 
tase, is converted into dextrose by prolonged coin with dilute 
sulphuric acid, and has the diffusibility of a dextrin, being nearest 
to the y-dextrin of Musculus.— Bull. Soc. Ch., I, xxxv, 368, Apr., 
1881. 
4, On etree: Acid.—LwkEs has tet sere established 
the existence of pentathionic acid. Continuous currents of hydro- 
gen sulphide and molphajoes oxide gases were ae “according 
ackenroder’s method, into distilled water, the former in 
slight excess, for seven hours, the mass heated on a water bath, 
filtered from sulphur and analyzed. Three separate methods 
gave in 10c.¢, 0°23, 0°227 and 0°226 of sulphur. On titrition, 1 
cc. neutralized 0°01457 gram K,O, equal to 0°012 gram potas- 
sium; thus giving 2: 4°55 for the ratio of K: S, and suggesting the 
presence of an acid having more sulphur than the tetrathionate. 
aving noticed that a partly neutralized solution decomposed 
only very slightly, Lewes added to a solution prepared as above 
a weak solution of barium hydrate, sufficient to neutralize ous 
half of it. On —- after — seyret Sande, hours, a clear 
op as 
obtained which proved on analysis to be barium pabares pee 
salt is soluble in cold wa r and if not too concentr ated the solu- 
tion may be oiled. The. reactions of the solution are y 
the same — > three potassium salts of pentat — “acid were 
obtaine n i-opake, prob rhombic ¢ 2,0, 
(H,0), ; enchant in small and apparently m odie cr ystals, 
having one molecule of water of crystallization; and ird in 
very small, short prisms, which is the anhydrous pentathionate 
K,S,0,. These salts may be easily prepared as they are 
the corresponding tetrathionates by the fact that they give an 
yma prec pre of sulphur op neers an alkali He ate,— 
0¢., ¥XXix, 68, March, 1 G. F. B. 
togr aphi C8: AN eries of Lea sons, accompanied by mde: 
is somewhat novel. After ziving in a clear and satisfactory We: 
on the upper half of the page, the matter culled from his o 
