1072 Experiments and Papers, [^No. 144. 



ten minutes, according to the season ; while this scarcely affects the 

 asphaltum, it softens the pitch into a ductile mass. 



Fouling by Marine Animals and Plants. 



19th. This serious evil, so familiar to navigators, and so importantly 

 exemplified in many of the papers submitted with this report, (see the 

 statements regarding the Phlegethon, the Sylph, &c.) has of course en- 

 gaged my attention, but as yet has led to no important results. Seve- 

 ral proposals have been made to prevent this by the use of poisonous 

 paints of different kinds. I do not anticipate much benefit from the 

 proposal. If the paints are soluble in water, they must wash off. If 

 insoluble, they are not likely to exercise any poisonous power. The 

 simplest way to test this would be, by immersing a log of nux- vomica 

 wood in Kyouk Phoo harbour, or any other place infested with the 

 Balani or Teredo. 



Singular inactivity of the water of the Baleaghaut Salt-works on tin 



plates. 



20th. While carrying on the experiments on tin plate, my stock of 

 Sea- water having been exhausted, I procured a quantity of brine in va- 

 rious stages of concentration from the Salt-works at Baleaghaut. 

 Tin plate immersed without protectors in this water, underwent no 

 change in four months, and the corrosion of iron was much retarded, 

 though not entirely prevented. The water was rich in organic matter, 

 and gradually became mouldy, as the experiments proceeded. This 

 singular fact opens a most interesting field for investigation, which 

 I regret much I have no longer the opportunity to pursue. 



Mr. Mallets Experiments. 



21st. When my experiments were nearly completed, a report on 

 those carried on for five years, and on a much larger scale, by Mr. Mal- 

 let in Dublin, reached this country, in the last volume of the " Proceed- 

 ings of the British Association." Mr. Mallet's copious tables of results 

 correspond so exactly with mine, that it becomes superfluous for me to 

 encumber your Board with details. I send the volume containing the 

 report, and which deserves the close attention of the Marine Board, 

 and of all Engineers connected with sub-marine-works in iron. 





