Bloodred Colour qf Water. 131 



Linnaeus also, in his journey through West Gotha, appears 

 to have first observed the colouring substance, which, in red 

 snow, has recently caused so much investigation. 



As the red rain at Brussels in 1646 had been tested by a dis- 

 tillation of the water, Dr Thomas Rau, in the same manner, 

 made chemical experiments on the bloody rain-water at Uim, of 

 15th November 1755. He indeed believed that the then fa- 

 vourite mechanical mixture of sulphur with water might be in- 

 ferred from his experiments ; but, from them, it is more probable 

 that the colour was caused by organic corpuscula in the water. 

 Both cases appear very similar, and, by a more rigid and com- 

 prehensive investigation, might have afforded a very different 

 result. — Nov. Act. Nat. Cur. ii. p. 85, seq. 



The blood-rain at Lucarno, in the south of Switzerland, of 

 14th October 1755, was connected with red atmospheric dust, 

 and is hence of great importance to Meteor ology.-^Ibid, 



At the same time there fell remarkable blood-coloured water, 

 caused by volcanic operations. The springs near the city of 

 Mequinez, west of Fez, after a great volcanic explosion, flowed 

 alternately with red coloured water. — Ibid. p. 90. 



In seamen's journals that treat of appearances of blood in sea- 

 water, we must take into consideration the possibility of very large 

 marine animals actually shedding blood, that may colour a calm 

 sea to a considerable extent. Johnson, de Piscibus, takes notice 

 of this appearance in a unicorn fish, whence it is quoted by 

 Baeck, in his treatise on the sword-fish (Istiophorus). — Acta. 

 Nat. Cur. viii. p. 212. 



De Saussure, in 1760, first examined, chemically, the colour- 

 ing matter of the red snow, and found it to be a vegetable mass, 

 on which account he was erroneously inclined to take it for the 

 pollen of flowers. — Voyage dans les Alpes, ii. § 646. 



Towards the conclusion of the 18th century, observers wit- 

 nessed other causes of blood colours. In 1790, a pond at Gie- 

 bichenstein, not far from Halle, exhibited a blood-red colour. 

 On this occasion Weber observed that the colour was caused by 

 very small microscopic animals, whose figure resembles that of 

 Miiller's Cercaria viridis.— Wagner, Naturkunde & Lander- 

 merkw. 1. Th. p. 143. 



In 1797 Girod Chantran, who observed an entirely similar ap- 



i2 



