lii Proceedings, fyc. 



granulation of zinc, &c . When the three varieties were admixed, 

 the deception, as far as external or accidental form was concerned, 

 was perfect. The specific gravity of the three varieties proved on 

 experiment to be — 



Gold-dust (spurious) 11.64 



Shottygold, ditto 12.06 



Nuggetty gold, ditto 11.11 



The average specific gravity was therefore 11.60, or about two- 

 thirds of that of Ballarat, or indeed, of Australian washed gold. It 

 may be remarked, that not a single particle of the sample, which 

 amounted to about 10 ounces troy, had escaped receiving its coat- 

 ing of pure gold. Any faulty particles had probably been dis- 

 covered and removed, by covering the manufactured article for a 

 few seconds with nitric acid. The material was therefore uniform 

 in its chemical composition. 



Dr. Macadam concluded by recommending gold buyers to protect 

 themselves against this rapidly increasing fraud, by using, not only 

 the usual chemical tests, but also the nitric-acid test, modified by 

 the prebminary addition of hydrochloric acid, as suggested by him, 

 and also the constant determination of the specific gravity of the 

 sample — the latter indeed being the most certain guide. 



Dr. Macadam read a paper entitled " On a New Guano Deposit 

 found in Port Phillip Bay." He stated that the Guano, which had 

 almost a white color, was very friable, and contained filaments of vege- 

 table matter, had been discovered on Mud, or Flat Island, Port Phillip 

 Bay, which is situated about five miles to the east of Queenscliff, and 

 about three miles from Point Nepean. The island, which consists of 

 a series of small islands, is irregular in its height at low water mark, 

 averaging from 3 to 12 feet above high water mark. The island 

 from which the guano is principally obtained is called Boatswain's 

 Island, but the guano also exists in large quantities in the Middle 

 Island. The islands are at present visited by great numbers of 

 cormorants and other sea birds. The existence of guano upon these 

 islands was known for some years back to the farmers residing in 

 'the neighbourhood of Mount Eliza and Queenscliff, who have fre- 

 quently availed themselves of the guano, and obtained successful 

 results from its use. The guano existed in a stratum about two 

 feet in thickness, extending over large tracts of the Boatswain's and 

 Middle Islands, and is covered, besides vegetation, with a layer of 

 about 15 inches in thickness of a rich dark chocolate soil, which is 

 highly charged with humus and earthy phosphates ; so rich indeed, 

 that vegetation proceeds almost too rapidly in the case of tuberous 

 plants, as the potato, &c. * 



The mean results of the chemical analysis of the guano, as obtained 

 from the examination of several samples, were as follow: — 



