CHAP. I.] THE EQUIPMENT OF THE SHIP. dl 
are all of the same height, 9 inches, and they pack convenient- 
ly upright in cases with wooden partitions and hinged lids, 
and padded at the bottom with cork. These jars are extreme- 
ly convenient, and wonderfully cheap: 200 cases complete, 
containing 2300 jars, were supplied by E. Breftit and Co., Up- 
per Thames Street, at a cost of 707. Besides these large store- 
bottles, there are many thousands of smaller stoppered bottles 
and corked test-tubes of different sizes and forms. Larger ani- 
mals are packed in cylinders of zine, which are made on board 
by a tinsmith as required. 
For preserving salpze, heteropods, and other surface animals 
containing much water, a solution of picric acid in water has 
been found very useful. A saturated solution at the ordinary 
temperature of England (say 5° C.) answers well, but picric 
acid becomes rapidly more soluble as the temperature rises ; 
and in the tropics a saturated solution is much too strong, and 
shrivels up delicate tissues. We have now on board a Carina- 
via, which, having lost its shell, was put into the picric-acid solu- 
tion as an experiment ; and after ten months it is still wonder- 
fully perfect, retaining the form and the transparency of the 
thick gelatinous mantle unimpaired. Ptero-trachea and Firola 
have been similarly prepared with success, and a portion of a 
huge Pyrosoma, five feet long, which was brought up in the 
trawl thus treated, is in excellent condition. Soft and pulpy 
animals, steeped for a few hours in a weak solution of chromic 
acid before being put in alcohol, have their tissues hardened, 
and retain their form. This process answers well for oceanic 
cephalopods and holothurians, which should be put in living, 
and allowed to die in the acid. A very weak solution of os- 
mic acid is of great value for killing and hardening small ge- 
latinous animals for microscopic preparations. A drop of a so- 
lution, one-tenth to one-fortieth per cent., may be added to a 
watch-glass of sea-water in which the creatures are; but they 
must not be allowed to remain more than a few minutes in 
