Intelligence atid Miscellaneous Articles. 47 1 



3939, is given among the errata printed at the end of tlie preface, 

 to Mr. Babbage's Logarithms, 



The errata so stated can scarcely be considered as errors, since 

 each copy contains the proper corrections. The history of that 

 particular mistake may be useful as pointing out the manner in 

 which they are sometimes introduced. Its origin in all the modern 

 tables arises from a misprint in Vlacq's folio edition of 1628, in 

 which a nine is printed instead of an eight in the 7th place of 

 figures. In the first three readings of the proofs of Mr. Babbage's 

 tables, they were compared with tables corrected by his own copy 

 of Vega, and this correction was included ; and it was rightly printed 

 3939. During the next three readings by a different set of readers, 

 copies of tables were accidentally employed, in which this had been 

 neglected to be corrected ; it was consequently altered to 3940. 

 The plates were now stereotyped, and in the 7th and 8th reading 

 it was again detected, and the source of its introduction traced. 

 The only error at present known in these tables is the misprint in 

 the logarithms of the number 13588, in which the fourth figure is 

 a large unity instead of a small unity. 



SILICA IN SPRINGS IS DISSOLVED BY MEANS OF CARBONIC 

 ACID. 



Dr. Karsten remarks, that, if so feeble an acid as the acetous, 

 is capable of dissolving silica, it is not improbable that the carbonic 

 acid may have the same property. This conjecture he has con- 

 firmed by experiment. The experiment may be made as follows. 

 Decompose a portion of liquor silicum by means of a superabun- 

 dance of any acid, the muriatic for example, and neutralize the 

 clear fluid with carbonate of ammonia, at the lowest possible tem- 

 perature. The carbonic acid evolved by this process combines with 

 the water; and, if the neutral fluid is preserved in a well-closed 

 glass vessel, it may be kept for many weeks, without exhibiting any 

 precipitation of sihca. But if it is exposed to the air, or, better, 

 if tlie solution is heated in an open vessel, it is decomposed in pro- 

 portion to the escape of the carbonic acid, and the siliceous earth 

 is deposited on the walls of the vessel in a-gelatinous state. This 

 result shows, that the great quantity of silica met with in many mi- 

 neral springs, particularly hot springs, is held in solution by carbo- 

 nic acid. It is true that we cannot in this way explain how the si- 

 liceous earth was first dissolved, — for the generally received opi- 

 nion, that the earth is simply washed out of the strata in the vici- 

 nity of the springs is, according to Karsten, untenable. — Edin. 

 Phil. Journ. 



NOTICE REGARDING THE COMMON STAR-FISH, ASTERIAS 



RUBENS. 

 On the 6th of March last year, M. Eudes Deslongchamps ob- 

 served the bead) at Colviile to be covered with star-fish. When the 

 waves retired, and there was still an inch or two of water upon the 

 Band, he saw them rolling out in the form of hails, which, on exami- 

 nation, he Ibund to consist of five or six individuals,, closely united 



and 



