1900-1901.] Prof. Letts and Mr Hawthorne on Ulm latissima. 273 
Wurtz’s Dictionnaire de Chimie the following statements are made 
under the article Acide Propionique \ — 
(1) Redtenbacher obtained propionic acid by exposing glycerine 
and yeast for several months at 20-30° C. [Liebig’s Annalen, 57 
(1845), p. 174.] 
(2) Keller, by fermenting bran and scraps of leather with 
chalk. [Liebig’s Annalen, 73 (1850), p. 205.] 
(3) Putrefaction of peas or lentils gives propionic and butyric 
acids. [Boehme, Journ. prakt. Chem., 40 (1847), p. 278.] 
(4) Fermentation of calcium tartrate. [Noellner, Liebig’s 
Annalen , 38 ( ), p. 299. Kickles, ibid., 61 ( ), p. 343. 
Dumas, Malaguti, and Leblanc, Comp. Rend., 25 ( ), p. 781.] 
(5) Propionic acid is stated to be produced by the fermenta- 
tion of glycerine and of sugar under certain circumstances. 
[Sfcrecker’s Lehrbudi der organischen Chemie, 5th edition (1867), 
p. 159.] 
While in Richter’s Organic Chemistry (English translation, 1900) 
none of these methods are mentioned, the only process of a similar 
kind for the production of the acid there alluded to being the 
fermentation of calcium malate and lactate. 
We therefore decided to prepare a quantity of the acid or acids 
which the fermenting ulva gives rise to, and to submit them to a 
careful examination. 
Accordingly, a considerable quantity of the well- washed seaweed 
was fermented with sea water at 37° C. in large flasks until no 
further evolution of gases occurred, which required about fourteen 
days. The resulting fluid was drained off from what remained of 
the seaweed and distilled with dilute sulphuric acid until traces of 
hydrochloric acid began to come over. The distillate was 
neutralised with caustic potash and evaporated to dryness, when 
about 25 grms. of solid residue were obtained. Experiments with 
weighed quantities of a known sample of potassium butyrate 
indicated that the best method for extracting the acid was to 
treat a strong aqueous solution of the salt with sulphuric acid, and 
then to extract with ether ; distillation of the dry salt with con- 
centrated sulphuric acid leading to considerable charring and loss. 
The dried residue was therefore dissolved in 80 c.c. of water, the 
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