1870.] INTRODUCTION OF SALMON INTO TASMANIA. 19 
hatched safely after being buried in ice 150 days, has been fully 
published to the world; but why this was likely to prove successful 
has not perhaps been publicly explained. Even Mr. Frank Buck- 
land, in his book on fish-hatching, speaks of freezing the ova, and 
thereby greatly misleads his readers. It was long ago shown that 
actually to freeze ova was to kill them in a few days, or, at most, weeks. 
The question then was, how could they be kept at an equable tem- 
perature just above the freezing-point? Ifa block of ice (the sen- 
sible temperature of which is 32° Fahrenheit) be immersed in water 
of a higher temperature, a portion of the ice will melt until the heat of 
the water falls to 32° F., but no more of the ice will be afterwards 
melted until the temperature of the water is again raised. If the 
ice could cool the water below 32°, a portion of the water would be 
frozen ; but to effect this, a further portion of the ice must be melted, 
and water at 32° is not capable of melting ice. If vessels contain- 
ing creams be immersed in ice for a month, no change takes place 
in their contents ; but convert a portion of the surrounding ice to 
water by the admixture of any deliquescent salt, and the submerged 
creams are instantly frozen. Therefore by this beautiful provision 
of nature any substance above the freezing-point buried in ice can 
never fall to the freezing-point till the ice next to it is converted 
to water ; and so long as any ice remains, the buried substance will 
continue ata low temperature certainly, but above the freezing-point ; 
and to this principle success was due. 
After many interviews with the owners of various ships, Mr. Youl 
(to whom Tasmania is greatly indebted for his determined perseve- 
rance in this respect) received the munificent offer from Messrs. 
Money, Wigram, and Co. of 50 tons of room gratis in their clipper- 
ship ‘Norfolk,’ bound to Melbourne. An ice-house capable of 
holding 30 tons was built in a situation admirably chosen for the 
purpose—on the lowest deck, amidships, and equidistant from stem 
and stern, in the position in which the motion of the vessel would 
be least felt. With much difficulty, and at the cost of great per- 
sonal exertion on the part of all concerned, ahout 90,000 ova of the 
Salmon (Salmo salar) and about 1500 ova of the Trout (Salmo fario) 
were obtained and safely packed in deal boxes, each a foot long, 8 
inches wide, and 4 inches deep. In some of the boxes a layer of 
charcoal was first placed on the bottom, then a layer of moss damped 
in pure water ; then ova were lightly placed on the moss, and the 
whole covered with another layer of damp moss, upon which the lid 
was screwed down. Inthe remaining boxes the charcoal was omitted, 
the packing otherwise being the same. Through the lid and bottom 
of each box several small holes were drilled; and all the ova were 
packed in 181 boxes. The boxes were next placed on the bottom 
of the ice-house, which was filled up with Wenham-Lake ice, and 
the whole securely closed. All being complete, the vessel sailed 
from London towards the end of January 1864, and left Falmouth 
on the 28th of that month. On the 15th of April the ‘ Norfolk’ 
arrived in Melbourne. On the next day the ice-hotise was opened 
and the small boxes unpacked. The lid of one box was then re- 
