16 THE VICTORIAN NATURALIST. 



an ocean swell and that above the crests of the waves must be 

 very great, and an albatross, in descending with the wind into the 

 trough or ascending against it above the crests, gains an increment 

 of relative velocity equal to this difference. That the wind above 

 the crests has a high velocity relatively to the waves is shown by 

 the familiar " white horses," and fishermen well know the danger 

 of losing the wind in the bottom of a trough. 



In conclusion, the albatross is a skilled aerial gymnast, which 

 has learned by experience to take advantage of the various 

 inequalities in the wind to gain in velocity relatively to the 

 surrounding air. I hope at some future time to pay a visit to 

 the island when the young birds are learning the art. It is 

 known that in the islands south of New Zealand they take a full 

 year of practice, and have to be driven off the nests by the old 

 birds when they return to breed. With a knowledge of this 

 theory, which is confirmed by every movement, to watch the 

 flight of an albatross has a never-failing interest. 



ON THE USE OF TURPENTINE IN MICROSCOPIC 



WORK. 

 Having lost several carefully prepared specimens of insects by 

 using as a final clearing agent the ordinary turpentine of the 

 shops, I was led to inquire into the matter, when I found that 

 the trade article is not the turpentine referred to in Davis's 

 "Practical Microscopy," p. 415, and Carpenter's "The Micro- 

 scope," pp. 441 and 442 (1891 edition) It is the natural balsam 

 which flows from the trees that is referred to, and not the distilled 

 extract sold as turpentine or oil of turpentine. 



The following definition is taken from Cooley's " Cyclopaedia 

 of Practical Receipts" (1892 edition), p. 1720 :—" Turpentine, 

 Turpentin, Terebinthina — an oleo-resin flowing from the trunk 

 (the bark being removed) of Pinus palustris, P. tteda, P. 

 sylvestris, and various species of Pinus and Abies. It is viscid, 

 of the consistence of honey, and transparent. By distillation it is 

 resolved into oil of turpentine, which passes over into the receiver, 

 and into resin, which remains in the still. Bordeaux, or French, 

 turpentine is from P. maritima. Chian turpentine is from P. 

 terebintlms. It is pale, aromatic, fragrant, and has a warm taste 

 devoid of bitterness. It is much adulterated, and a fictitious 

 article is very generally sold for it. Venice turpentine is the 

 liquid resinous exudation from the Abies larix. It is sweeter 

 and less resinous tasted than common turpentine, but is now 

 scarcely ever met with in trade. That of the shops is wholly a 

 fictitious article." 



In Carpenter, p. 442 (1891 edition), it is stated that the natural 

 balsam has a peculiar power of rendering the chitinous textures 

 of insects transparent. — H. Bullen. 10th February, 1896. 



