196 Scientific Intelligence. Chemistry. 



solid carbonic acid begins to melt at 185 Fahr., and starting at 

 this point, the temperature does not vary any more. Thus we 

 can obtain from this extreme limit a point as fixed as is supplied 

 by that of melting ice. If, after having formed a small coppel 

 of solid carbonic acid, we pour into it three or four drachms of 

 mercury, it is seen to congeal in a few seconds, and to remain 

 in this new condition so long as an atom of solid carbonic acid 

 remains, that is to say, for twenty or thirty minutes when the 

 weight of the eoppel is from two to three drachms. I have al- 

 ready said that the addition of ether or alcohol did not augment 

 the real degree of the cold, but, by giving the solid carbonic acid 

 the power of moistening bodies, and of adhering more intimate- 

 ly to their surface, these substances much increase the frigerating 

 effects. A piece of solid carbonic acid, on which some drops of 

 ether or alcohol are poured, becomes capable of congealing 

 fifteen or twenty times its weight of mercury. The prompti- 

 tude with which it is converted into the solid state, the mass in 

 which it is effected, and which may easily exceed half a pound, 

 and its continuance in this new condition, which may be main- 

 tained as long as you like, with the single precaution of placing 

 the metallic mass upon a base of solid carbonic acid, leads me to 

 believe that this method of freezing mercury will henceforward 

 be substituted for all those which have been previously employed/' 

 11. Mode of preventing Beer from becoming acid. A patent 

 has been taken out in America., for preserving beer from becoming 

 acid in hot weather, or between the temperatures of 74 and 94. 

 To every 174 gallons of liquor, the patentee Mr Storewell di- 

 rects the use of one pound of raisins, in the following manner : 

 " Put the raisins into a linen or cotton bag, and then put the bag 

 containing the raisins into the liquor before fermentation ; the 

 liquor may then be let down at 65 or as high as 70. The bag- 

 containing the raisins must remain in the vat until the process 

 of fermentation has so far advanced as to produce a white ap- 

 pearance or scum all over the surface of the liquor, which will 

 probably take pldce in about twenty-four hours. The bag con- 

 taining the raisins must then be taken out, and the liquor left 

 until fermentation ceases. The degree of heat in the place 

 where the working vat is situated, should not exceed 66 nor be 

 less than 60." To prevent distillers'' wash from becoming acid, 



