222 Mr. B. C. Brodie's Investigation on the 



the fluid which passes through the filter carries no substance 

 with it. The first portions of alcohol will contain consider- 

 able portions of a wax matter having a lower melting-point 

 than the cerine, and having the appearance of the residue 

 undissolved by the hot alcohol. 



The lead salt is to be decomposed by very strong acetic 

 acid. The substance which separates, after having been well- 

 washed with boiling water, is to be dissolved in absolute 

 alcohol, and the solution, while hot, filtered. On the cooling 

 of the alcohol a substance will crystallize out in fine granular 

 crystals. This substance melts at about 78° C. It is highly 

 crystalline on cooling from the melted state. Very carefully 

 prepared, it gave on analysis the following numbers. The 

 analysis was made with chromate of lead. 



0*26 grm. of substance gave 0*753 grrn. of carbonic acid 

 and 0'307 grm. of water. 



These analyses give in 100 parts — 



Carbon .... 78*98 

 Hydrogen . . . 13-12 

 Oxygen .... 7*90 



100-00 

 This corresponds to the formula C^ H^O^ 



Atomic weight. Calculated in 100 parts. 

 C 54 . . . 324 79*02 



H^. . . 54 13-17 



O a . . . 32 7-81 



410 100*00 



It is very difficult to wash this lead salt perfectly out. Even 

 in the present case, after the greatest care, I obtained a trace 

 of a substance, soluble in aether, on attempting further to 

 purify the substance by combining it with baryta and washing 

 out its baryta salt. This makes no difference in the numbers 

 or the melting-point. But it is advisable to prepare the pure 

 acid by boiling the acid as separated from the lead salt with 

 caustic potash, precipitating the baryta salt by a large excess 

 of chloride of barium, and carbonate of soda ; washing this 

 well out with aether; decomposing with an acid, and crystal- 

 lizing the resulting substance repeatedly out of alcohol and 

 aether. The acid prepared in this manner melted at 78°, 

 79° C, being the same melting-point as the acid sepaiated 

 from the lead salt; it gave to analysis the following numbers: — 



I. 0*263 grm. gave 0*7583 carbonic acid and 03085 water. 



II. Another preparation. 0*2615 grm. gave 0"7558 car- 

 bonic acid and 0*307 water. 



