Tannin has no action on it, but basic acetate of lead produces a gelatinous precipitate in its aqueous solution.  Strange enough, this precipitate is entirely soluble in a small excess of basic acetate of lead.  If thrown into concentrated sulphuric acid, sapotin colors it with a garnet red tint.  It does not reduce Fehling’s solution.  Its analysis gave the following results: 

Calculated for                     Found. 
C_{29}H_{52}O_{20}.          I.               II.

C          48.33                 48.69             48.31
H           7.23                  7.33              7.45

When heated with water and a little sulphuric acid, sapotin is decomposed and yields glucose and an insoluble matter which I call sapotiretin.  One hundred parts of sapotin produce 51.58 parts of glucose and 49.67 of sapotiretin.  The equation which represents this reaction is: 

C_{29}H_{52}O_{20} + 2H_{2}O = 2C_{6}H_{12}O_{6} + C_{17}H_{32}O_{10}

and requires 50 per cent. of glucose and 55 per cent. of sapotiretin.

Sapotiretin is an amorphous compound, insoluble in water, very soluble in alcohol, less soluble in chloroform, insoluble in ether.  Below is the result of its analysis: 

Calculated for                      Found. 
C_{17}H_{32}O_{10}.          I.                  II.

C          51.52                 51.51                51.20
H           8.08                  8.19                 8.34

—­Amer.  Chem.  Jour.

* * * * *

DETECTION OF PEANUT OIL IN OLIVE OIL.

Holde, after a careful trial of the various processes for detecting the above adulteration, gives the preference to Renard’s, which he describes as follows: 

Ten grms. of the suspected oil, after being saponified, and the fatty acids separated by hydrochloric acid, are dissolved in 90 per cent. alcohol, and precipitated by sugar of lead.  The oleate of lead is separated by ether, and the residuum, consisting of palmitic and arachic acids, is decomposed by hydrochloric acid.  The fatty acids are dissolved, with the aid of heat, in 50 c.c. of 90 per cent. alcohol.  The arachic acid which separates after cooling is filtered out and washed, first with 90 per cent. and afterward with 70 per cent. alcohol.  It is then dissolved in hot alcohol, and the solution evaporated in a weighed saucer.  The weight of the residuum, after taking into account the acid dissolved in the alcohol, equals the whole amount of arachic acid contained in the oil; the melting point of this residuum should be 70 deg. to 71 deg.  C. With this process the author has always been successful; but when the olive oil contains not more than 5 to 10 per cent. of peanut oil, it is necessary to make the test with 40 grms. of the former, otherwise the melting point of the arachic acid cannot be estimated.  Furthermore, the acids which are separated from the lead salt by hydrochloric acid must be recrystallized repeatedly with 90 per cent. alcohol, until the melting point ceases to rise, in case the latter is not found to exceed 70 deg.  C. at the first estimation.  When peanut oil is present, the melting point will always be above 70 deg..—­Chem.  Zeit.