150 Intelligence and Miscellaneous Articles. 



common sea sand of the Dublin coasts, and a few microscopic flakes 

 of mica. 



A singular minute black worm is found in this clay, which may be 

 worth the attention of naturalists. 



The clay as dug out does not effervesce with acids, and is insolu- 

 ble in them. It yields no soluble matter to water, and appears to 

 contain no alkali in any specimens yet examined. I have, however, 

 reason to think that the less fully decomposed portions of the clay 

 may contain alkali in a soluble condition, and hence render the ma- 

 terial valuable as a manure. 



Some of the finest portion of the clay washed from the sand, and 

 dried at a temperature of 212° Fahr., was found by me to have the 

 following composition : the analysis having been conducted in the 

 usual way and with the usual precautions, it does not seem necessary 

 to detail its steps : — 



Silica 67-96 



Alumina 23-20 



Lime 3-23 



Magnesia .... 0-63 

 Oxide of iron. . ri9 



Water 2-80 



99-01 

 As no washing completely removes the presence of sand from this 

 clay, which always feels gritty to a glass rod, and as it contains 

 comminuted mica, it could not be expected that its analysis should 

 present a precisely mineralogical result. 



From the close analogy however which the above figures present 

 to the composition of various felspathic rocks as analysed by Beu- 

 dant, Berthier, &c., there can be little doubt but that the geologic 

 origin of this clay is the decomposition of felspar, or other granitic 

 allied minerals ; in fact the results approximate to the formula 

 (taking the iron and manganese together) 



AH- Si + Ca + (Mg + FcO) + HO, 

 or 3(A1 + Si,) + (Ca + Sij) + ((Mg + FcO) + Sij) + HO. 



This clay is of very great ceconomic value, and capable of being 

 used for the manufacture of porcelain ; it has, however, hitherto only 

 been brought into use for the manufacture of crucibles by the writer. 

 I am. Gentlemen, your obedient Servant, 

 Dublin, June 24, 1844. Robert Mallet. 



EASTER DAY, 1845. 



[In furtherance of the object stated in the following notice by 

 Prof. I)e Morgan, we copy it from the Athenaeum (No. 872).] 



In an article which I have prepared for the next number of the 

 Companion to the Almanac, I have discussed the reasons why Easter 

 Day will next year fall, in apparent defiance of the Act of Parliament, 

 upon the very day of the full moon. But as an accidental application 

 which I have received (and I know that the Superintendent of the 

 Nautical Almanac has received another from a different quarter) 



