246 Proceedings of Royal Society of Edinburgh. [sess. 
Metliylacrylic Acid . — From the ethereal product of the electrolysis 
of ethyl-potassium dimethylmalonate a fraction boiling between 
115° and 125° was obtained. From this, by saponification, and 
decomposition of the potassium salt with acid, the acid was pre- 
pared. It was purified by recrystallising its calcium salt. The 
purified acid had, when warmed, a very penetrating smell, and de- 
colorised bromine in solution in bisulphide of carbon. When 
heated to about 130° it was suddenly transformed into a white solid 
mass, which agreed in all respects with the description given by 
Fittig and Engelhorn* of the polymer of methylacrylic acid. 
Dried at 130-135 it gave the following results on combustion : 
0T396 gr. gave 0*2846 gr. CO2 and 0*0881 gr. H2O. 
Calculated for (C4Hg02)„. Found. 
C . . . 55*81 55*60 
H . . . 6*97 7*01 
The potassium in the potassium salt of the original acid was de- 
termined. 
0*2895 gramme gave 0*2024 gramme K2SO4, i.e. 31*4 per cent, 
potassium, as compared with 31*5 calculated for KC4H5O2. When 
cooled wdth ice the acid solidified, and fused again at 14°. Metbyl- 
acrylic acid fuses at 16°. 
Ethylcrotonic Acid . — As already mentioned, a considerable part of 
the ethereal product from the electrolysis of ethyl-potassium diethyl- 
malonate boiled at a comparatively low temperature. From a 
fraction boiling between 150° and 170°, ethylcrotonic acid was pre- 
pared by the method described for methylacrylic acid. The purified 
acid fused at 41°-42°. Ethylcrotonic acid fuses at 41°. f 
Combustion gave the following results: — 0*1285 gramme gave 
0*2969 gramme CO2 and 0*1027 gramme H2O. 
Calculated for CgHioOg. Found. 
C . . . 63*16 63*02 
H . . . 8*77 8*88 
The dibromide was prepared from the acid. It fused at 80°. 
Fittig and Howe gave 80° *5 as the fusing point. J 
* Fittig and Engelhorn, Liebig's Annalen 200, 70. 
t Fittig and Howe, Liebig's Annalen 200, 23. 
X Liebig's Annalen 200, 35. 
