294 
OXALIC ACID IN PERUVIAN GUANO. 
and after standing several hours strain off the thick mucila¬ 
ginous liquid by pressure in a loose-textured cotton cloth. 
Return the rennets to the dish, sprinkle on the remainder of 
the salt, again repeat the process of malaxation, maceration, 
and expression. Let these operations be repeated a third 
time, or until the fluid obtained measures forty-two fluid 
ounces; then, having mixed the alcohol with the wine, 
add them to the expressed liquid, and agitate the mixture 
several times at intervals of an hour or two; after which 
allow it to stand till the mucus which is precipitated by the 
alcoholic addition subsides, when the nearly clear solution of 
rennet may be drawn off with a syphon, and filtered for use. 
The wine may be substituted by a mixture of one part of 
alcohol and three parts of water. A tablespoonful of this 
solution readily coagulates a quart of milk to a firm curd, if 
added after gently w'arming the milk (to about 100° F.), 
stirring it well for a moment, and allowing it to stand un¬ 
disturbed for half an hour or an hour. Cold custard is made 
in the same manner by previously adding a tablespoonful or 
more of sugar, and some vanilla or other flavouring before 
adding the rennet. When liquid rennet is employed for 
medicinal purposes it is preferable to make it with wine, 
as being more acceptable to the stomach.— Am. Jmirn. 
Fharmacy. 
OXALIC ACID m PERUVIAN GUANO. 
By M. Liebig. 
a 
Almost all the guano now so extensively used in Europe 
is obtained from the New World. This natural manure, 
composed essentially of urate and oxalate of ammonia, phos¬ 
phate and oxalate of lime, and a peculiar base, guanine, is, it 
is well known, the produce of certain sea birds. 
M. Liebig, whose works have rendered so much service to 
agriculture, has recently published a memoir in the Annalen 
der Chemie und Pliarmacie, vol. cxix. p. 11, 186l, which to us 
appears to throw great light on the cause of the fertilising 
properties of guano, and on the means of appreciating them 
by the aid of chemical analysis. 
The manifest action of Peruvian guano on the soil has not 
hitherto, he says, been satisfactorily explained. The good 
effects of this manure are generally attributed to the large 
proportion of nitrogenized matters which it contains,— 
matters consisting chiefly of ammoniacal salts and uric acid. 
Many observations, however, have proved that a field manured 
