142 The Rev. S. Haughton on the Joint Systems [Feb. 25, 



Dimethoxalic acid is a white soHd, readily crystallizing in beautiful prisms 

 resembling oxalic acid. It fuses at 75°* 7 C, volatilizes slowly even at com- 

 mon temperatures, and readily sublimes at 50° C, being deposited upon a 

 cool surface in magnificent prisms. It boils at about 212° C, and distils 

 unchanged. Diraethoxalic acid reacts strongly acid, and unites with 

 bases, forming a numerous class of salts, several of which are crystalline. 

 In addition to the baryta-salt above mentioned, we have examined the silver- 

 salt, which is best formed by adding oxide of silver to the free acid, heating 

 to boiling, and filtering, when the salt is deposited in star-like masses of 

 nacreous scales as the solution cools. On analysis, this salt gave numbers 

 closely corresponding with those calculated from the formula 



fCH, 



c,"x o 



I OH 



10 Ag 



Attempts to produce an ether by digesting the free acid with absolute 

 alcohol at a temperature gradually raised to 160° C. proved abortive, traces 

 only of the ether being apparently formed. 



Thus the final result of the action of zinc upon a mixture of iodide and 

 oxalate of methyl is perfectly homologous with that obtained by the action 

 of zincethyl upon oxalic ether. In the methylic reaction, however, no 

 compound corresponding to leucic ether was obtained. This cannot create 

 surprise when it is remembered that dimethoxalic ether approaches closely 

 in composition to lactic ether, which is well known to be instantly decom- 

 posed by water. We have sought in vain to obviate this decomposition of 

 dimethoxalic ether by adding absolute alcohol in place of water to the pro- 

 duct of the reaction. 



February 25, 1864. 



Major-General SABINE, President, in the Chair. 



I. "On the Joint Systems of Ireland and CornwaU, and their Me- 

 chanical Origin.^^ By the Rev. Samuel Haijghton, M.D._,r.R.S., 

 Fellow of Trinity College, Dublin. Received February 8, 1864. 



(Abstract.) 



This paper is a continuation of a former paper " On the Joints of the 

 Old Red Sandstone of the Co. Waterford,'* published in the * Philosophical 

 Transactions ' for 1858, and contains the results of the author's observations 

 for some years, in Donegal, the Mourne and Newry Mountains, Cornwall, 

 and Fermanagh, with deductions from theory. 



The author establishes the existence in Waterford of a Primary Conjugate 

 System of Joints, and of two Secondary Conjugate Systems, lying at each 

 side of the Primary at angles of 27° 5' and 37° 11'. 



