NATURAL PHILOSOPHY. 137 



developments. The column of cloud is seen to divide into two 

 j)arts near the middle of the tube, and in one experiment a globe 

 of cloud formed at the centre with axes projecting right and left. 

 Sudden commotions were observed in the nebulous mass, buds of 

 cloud shooting out and growing into liower-like forms. In one 

 case the cloud-bud grew rapidly into a serpent's head ; a mouth 

 was formed, and from the mouth a cord of cloud, resembling a 

 tongue, was rapidly discharged. 



The aqueous vapor of hydrobromic acid mixed with air gave 

 rise to the formation of two clouds 5 inches apart, and united by a 

 slender cord of cloud of the same bluish tint as themselves. 

 After undergoing various modifications of form, both clouds pre- 

 sented the appearance of a series of concentric funnels set within 

 one another, the interior ones being seen through the gaseous 

 walls of the outer ones. As many as 6 of these concentric funnels 

 were observed. 



The aqueous solution of hydrochloric acid yields a vapor which 

 required an exposure of 15 or 20 minutes to the electric light for 

 the production of a fully developed cloud. It was then divided 

 into several sections, united to each other by a slender axis. 

 "Each of these sections," says Dr. Tyndall, " possessed an ex- 

 ceedingly complex and ornate structure, exhibiting ribs, spears, 

 funnels, leaves, involved scrolls, and tridescent fleurs-de-lis. 

 Thus the structure of the cloud from beginning to end was per- 

 fectly symmetrical ; it was a cloud of revolution, its correspond- 

 ing points being at equal distances from the axis of the beam." 



The aqueous vapor of hydriodic acid yields a nebula which so 

 far resembles those of the two preceding acids that the process 

 commences by the formation of two small clouds united by a 

 cord ; but it exhibits more vivid colors (green and crimson) than 

 the other vapors. Of the various substances experimented on, 

 none gave such astonishing results as this. "The development 

 of the cloud," says Dr. Tyndall, "was like that of an organism, 

 from a more or less formless mass at the commencement, to a 

 stiHicture of marvellous complexity;" and this grand simile is 

 fully borne out by his description of the changing phenomena 

 which he observed. After a time the cloud formed into a spectral 

 cone with a circular base, from which filmy drajDery seemed to 

 descend. On this base was an exquisite vase, with a vase of 

 similar shape in its interior, and from the' edges of the vases fell 

 the fiiintest clouds. The anterior portion of the cloud assumed in 

 succession the forms of roses, tulips, and sunflowers ; it also pre- 

 sented the appearance of a series of beautifully shaped bottles 

 placed (like the funnels in a previous case) one within the other; 

 and once it positively assumed the form of a lish, with eyes, gills, 

 and feelers. " The twoness of the animal form," says the ob- 

 server, " was displayed throughout, and no disc, coil, or speck 

 existed on one side that did not exist on the other." For nearly 

 two hours Dr. Tyndall looked in wonder at the extraordinary 

 vision which his magie skill had evoked. 



These experiments are capable of almost any degree of modifi- 

 cation and extension. They have already revealed to us a new 



12* 



