23» ^^ PREVENTING THE DECAY OF SKIPS. 



the navy, by which it appeared, that there were thirty ships, 

 called nevT ships, which, as he obstrves, *' for want of pro- 

 " per care and attention, had toadstools growing in their 

 ** holds as bi<^ as his fists, and were in so complete a state of 

 •** decay, that some of the planks had dropped from their 

 ** sides." From that time to the present, the evil has in 

 some measufe existed ; and, although it has not since ap- 

 peared in so great an extent as it then did, yet the state of 

 «nd at preien^ some ships recently launched botli justifies and demands all 

 possible inquiry as to the cause;? of the growth of this fun- 

 Attempts to gus, and its prevention. Several means have been tried to 

 ismeriv i: prevent its vegetating, many of which might have answered 

 this purpose, had they not been found to introduce evils as 

 great as that which they pretended to cure. Among the 

 most prominent, was the mode practised on the timbers of 

 by salt many ships, between the years 1768 and 1773, by saturat- 



ing them with common salt ; but this was found to cause a 

 rapid corrosion in the iron fastenings, and the ships were 

 (between decks) in a continual state of damp vapour. Mun- 

 dic, found in the mines in Devonshire, has been lately era* 

 and mundic. ployed, in fusion, to eradicate the vegetation, and prevent 

 its future growtii ; but time is required to prove its efficacy. 

 Production of In the common mode of constructing ships there are seve- 



carbomc acid j.jjj causes, which promote the growth of fungi. The accu- 

 gas unj uncus- ^ ° ° . 



roulation and consequent fermentation of materials not suf- 

 ficiently seasoned, divested too of a free circulation of air» 

 and permitting sap to remain on the edges of the frames, 

 generate carbonic acid gas to the prejudice of the timber, 

 and which promotes the growth of this boletus. Mr. Hum- 

 boldt has found by experiments, that eight or ten hun- 

 dredths of carbonic acid gas, added to the air of the atmos- 

 phere, rendered it extremely fit for vegetation; and that the 

 air in mines, and other subterraneous passages, was found in 

 this state, which is very' favourable to the germination of all 

 plyints of the class cryptogamia. The gas found in the 

 openings between the timbers of ships affected with the dry 

 rot has been proved, to be precisely what Mr. Humboldt 

 has mentioned. 

 Means pro- '^^^ means, that I propose to prevent or cure this evil, are , 



posed to pre- twofold; «harring the whole surfaces of the timbers, and 



th? 



