12 
one of our home industries has lately been adopted, namely the 
preservation of butter for a lengthened period by means of salicylic 
acid. A very small portion of the acid is dissolved in two parts of 
lactic acid and ninety-eight parts of water; this mixtute is used in 
the proportion of one grain of salicylic acid to one hundred kegs of 
butter, and will keep the latter fresh for an almost indefinite 
period. 
In my last annual address I mentioned the sponge industry at 
Gratz. Since then an interesting report has been issued of the 
sponge farms of Cuba, in which it appears that the demand of these 
sponges is likely to be an increasing one. They do not, of course, 
equal the fine Turkey sponges in texture, yet they are largely 
employed in damping tobacco, and also in cleaning the machinery 
in use on the sugar estates. In the Isles of the Bahamas, poeti- 
cally termed the ‘land of the pik pearl,” the sponge farms alone 
give occupation to upwards of five thousand people. In Florida, 
too, successful experiments of sponge growing have been made, 
but the chief drawback to this industry is, that under the most 
favourable circumstances, the farmer must wait five or even seven 
years before his first crop is available. Therefore sponge farm- 
ing, like tree planting, may be considered somewhat ‘‘an heroic 
culture !”’ 
Photography, which is both a science and an art, held what may 
be called its Jubilee exhibition last March at the Crystal Palace. 
Could Col. Daguerre and Fox Talbot themselves see the vast strides 
this art has made since their day, they would indeed feel proud to 
have inaugurated an art which has attained such superb results, 
both artistically and scientifically. The perfection of the photo- 
graphic instruments, and the artistic merit of the pictures exhibited, 
called alike for the highest praise. The little floating magnesium 
lamps have improved, and form a valuable and ready means of 
taking views independently of sunshine. In connection with this 
elaborate photographic display, a special feature was the admirable 
finish of the oxyhydrogen lanterns for exhibiting many of the 
photographs. The high pressure of 3,000lbs. to the square inch, 
by which the gases are now forced into steel tubes to supply the 
light, is reduced by a simble appliance in the jet, which impmges 
on the hard lime wick, giving a small but most intense light, and 
one eminently suited for lantern lenses. The screen too on which 
the views were presented is prepared in a novel manner, by cover- 
ing the canvas with an enamel of white zine paint, which prevents 
the woven texture showing through the smooth surface, and thus 
much enhances the clearness and beauty of the views. 
There is no scientific poi: t which is still undergoing more search- 
ing investigation than that of the influence of bacteria, and various 
