204 Prof. Williamson on the Preparation of 



ADC and BEC respectively. Produce AC to n, and make the 

 angle nCM = ADC -f CDE, and draw CM cutting the circle on 

 AC in M : again produce BC to ?n, and make the angle mBN = 

 DEB -f BEC ; also draw BN cutting the circle on BC in N. Join 

 MN, and it will cut the circles in D and E, the points required. 

 The demonstrations need not be added, since they are suffici- 

 ently obvious from the constructions and the known property 

 that the exterior angle of any inscribed quadrilateral is equal to 

 the opposite interior angle*. 



Burnley, Lancashire, 

 June 29, 1853. 



XXX. Note on the Preparation of Propionic and Caproic Acids, 

 By Professor Williamson f. 



IN the August Number of the Philosophical Magazine I 

 observe a paper by Dr. Wrightson, describing the action of 

 an alcoholic solution of hydrate of potash upon a mixture of the 

 cyanides of sethyle and amyle, and employing the result of that 

 experiment as an argument against the othyle theory. The 

 author reasons on the assumption, that, of two results which he 

 conceived possible, the one he obtained must be unfavourable to 

 the othyle theory, the other favourable to it. It is to be regret- 

 ted that the author did not endeavour to describe the grounds 

 of this assumption — to show us the connexion between each 

 result and the corresponding theory ; for I think he could then 

 hardly have failed to perceive that his assumption is erroneous. 

 The result which he failed in obtaining is incompatible with the 

 othyle theory of which he conceived it a consequence, and the 

 result he obtained is decidedly confirmatory of the theory which 

 he expected it to upset. 



The othyle theory represents acetic acid as containing the 

 radical C 2 h 3 (derived from tethyle, C 2 h 5 , by the substitution 

 of O for h 2 ). It connects the formulae of the acetic series with 



that of water, , 0, by writing them in the following manner : — 



Formic acid . . . C h n 

 h U 



Acetic acid . . . C 2 h 3 O n 

 h U 



* Mr. Burrow's journals will shortly be presented to the Library of the 

 Royal Astronomical Society, and may there be consulted by those who are 

 desirous of seeing more of the occasional jottings of this somewhat eccen- 

 tric but able mathematician. 



t Communicated by the Author. 



