June 1st, 1887.] 



SCIENTIFIC NEWS. 



is fixed in the roof, and there is a short tube with a mouth- 

 piece in the bell. The apparatus described was devised by 

 Mr. W. A. Gorman, and is made by Mr. A. E. W. Gwyn, 

 of 9, Ducks-foot Lane, London. 



THE DECAY OF LEATHER-BOUND 

 BOOKS. 



SOME years ago Dr. Angus Smith* observed that the 

 leather in his bookcases became rotten in exact pro- 

 portion to the height above the ground. At the top of the 

 room the leather became so friable that it could scarcely be 

 handled ; near the ground it was still pretty firm ; the in- 

 termediate levels were aflected according to their height. 

 Gas was commonly burned in the room, and Dr. Smith 

 attributed the decay of the leather to sulphuric acid, formed 

 as a product of the combustion of impure coal-gas. The 



glossy surface by burnishing, and it is probable that this 

 starchy mess furnishes a medium well filled for the spread of 

 a mould. Heat and foul air favour such growths, and mould, 

 as well as sulphuric acid, forms rapidly in the upper air of 

 a hot room. Bad leather, without antiseptic treatment, aided 

 by a glaze due to starchy paste, will account for the decay 

 of leather binding, whether gas is burnt or not; but it must 

 be admitted that the products of combustion of impure gas 

 hasten the process in a startling degree. 



A reinedy for this evil exists. Books may be bound 

 without extravagant cost, in a way which eftectually checks 

 the ravages both of gas and mould. Use no calf or russia 

 under any circumstances. Bind valuable books, or such as 

 are to endure much wear, in half-morocco and the rest in 

 cloth. See that the sheets are sewn, not upon strings, but 

 upon broad tapes. Make each side of the cover of two 

 good millboards glued together, and pass the tapes between 



DIVING BELL WITH SrEAKLXG AITAR.VTUS. 



experience of many other sufterers tends to confirm Dr. 

 Angus Smith's explanation, but it may be questioned 

 whether sulphuric acid is the sole destroyer of the leather in 

 books and bookcases. 



To begin with, some books are much more rapidly 

 affected than others. Ordinary glossy calf, law calf, and 

 russia perish first. Good morocco, lettered in gold (not 

 Dutch metal), will resist indefinitely ; and here and there a 

 calf-bound volume is found to be uninjured, while its neigh- 

 bours right and left have fallen to pieces. This exemption 

 of particular books suggests a destroying agent more selective 

 than mineral acids. Moreover, it has been observed that 

 the crumbly leather from the hinges of a decayed bound 

 book exhibits, when examined under the microscope, fine 

 filaments, the thread or mycelium of a mould. The books 

 which perish most rapidly and certainly are those which 

 have been coated over with a paste wash, in order to get a 



* " Air and Rain," p. 52S, 



the boards. To make sure that this is done right, and that 

 the millboard is of good quality examine the book for your- 

 self before the end-papers are fastened down. Books thus 

 bound need not cost more than the perishable half-calf now 

 in ordinary use, and this is said upon the authority of a 

 specification and estimate which have regulated the binding 

 of several hundred books. Honest leather or sound cloth 

 will not soon perish, even in a foul and heated atmosphere. 



THE SPECTRUM.— L 



SIR ISAAC NEWTON, writing to Oldenburg, on Jan- 

 uary iSth, 167 1, proposes to communicate to the 

 Royal Society " an account of a philosophical discovery, 

 being in my judgement the oddest, if not the most con- 

 siderable detection which hath hitherto been made in the 

 operations of Nature." This discovery was communicated 

 on February 6th, and excited great interest among the 

 members, and " the solemn thanks " of the meeting were 



