416 



Seventh Meeting. November 15, 1869. 



The Rev. D. Bruce in the chair. 



The names of two new members were announced : — Messrs. Hugh Hart Luslc, and 

 George Thompson Chapman. 



A list of donations to the Museum was read by the Secretary. 



Papers read :— 



(1.) " On the occurrence of the New Zealand Frog (Lelopelma Hochstetter'i) at the 

 Puriri Creek, Thames ; with an Account of a peculiar feature in the habits of an Aiis- 

 tralian Frog," by Alexander Aitken, second officer of the late Victorian Exploring 

 Expedition. (See ante, p. 87. ) 



A specimen of Leiopelma Hochstetter'i, from Puriri Creek, accompanied the paper. 



(2.) "On Drainage ©iterations at the Remuera Swamp," by J. Baber, C.E. (See 

 ante, p. 219.) 



In the course of the discussion which ensued, Mr. Baber drew attention to the 

 numerous subterranean currents of water in the lava field of Mount Eden, and which 

 formed the source of supply to the swamps and streams having their outlet at Coxe's 

 Creek. Certain wells in the Epsom district appear to tap these streams, as they are never 

 dry, while other wells, within a few yards even, and at much greater depths, are often 

 dry. 



Dr. Purchas remarked that after the floods of Ash Wednesday last, when the traffic 

 was stopped at Penrose, new springs broke out in Onehunga, and continued in operation 

 for some time. Wells sunk through the scoria in Onehunga yielded at the same level ; 

 but there was a difference of ten or twelve feet in the height of the water during the 

 summer and winter seasons. A lava field was like a vast sponge, collecting the surplus 

 water of the winter and storing it for future use. 



Mr. W. Buckland considered that the flood at Penrose was in all probability caused 

 by the discharge from the Ellerslie slaughter house having blocked up the usual outlet 

 from St. John's Lake, and forced it to seek another channel. 



Dr. Purchas said that Mr. Buckland' s statement at once explained what had been 

 a great puzzle to the inhabitants of Onehunga ; their water supply, usually remarkable 

 for its extreme purity, had of late been slightly tainted. 



(3.) " On the Naturalized Plants of New Zealand, specially with regard to those 

 occurring in the Province of Auckland," by T. Kirk. (See ante, p. 131.) 



Mr. W. Buckland observed that he had lately observed the so-called Chilian 

 groundsel in great abundance, and of unusual luxuriance near Taupo. He should like to 

 know if Mr. Kirk considered the Rat's-tail grass native or introduced. 



Dr. Purchas remarked that he had listened to the reading of the paper with great 

 interest, and trusted the interesting questions it suggested would receive the attention 

 they merited from members of the Institute during the recess. 



Mr. Kirk stated that the so-called Chilian groundsel was Erigeron canadensis, a native 

 of North America, which, since the middle of the seventeenth century, had spread over 

 the world. The Rat's-tail grass was Sporobolus elongatus, and he believed it to be a true 

 native ; although an exotic grass, Selaria italica, which Mr. Bassett informed him had 

 been introduced within the last ten years was often growing with it in the Otahuhu 

 district. He pointed out the value of records of the first appearance of naturalized plants 

 in any district with regard to the important subject of their powers of diffusion, and 

 urged the members of the Institute to place facts of this kind upon record. 



(4.) "On Improvements in the Processes for extracting and saving Gold," by 

 T. Heale, C.E. (See ante, p. 174.) 



Dr. Purchas remarked that he considered the mode of assay and separation, suggested 

 by the author of the paper, just read, not only feasible, but the best that had been 

 proposed ; it was, in fact, identical with the first process employed by Mr. P^ansen, in 

 the production of his patent concrete, he dissolved flints in caustic potash under pressure ; 

 and auriferous quartz differed essentially from flint only in the presence of metals. 



Mr. James Stewart spoke of the ease with which pressure could be applied by mean3 

 of steam ; the material to be operated upon being placed in iron retorts furnished with 

 safety valves, and surrounded by clay. He believed that specimen-crushings would 

 never take place if this plan were adopted. 



Mr. W. Buckland considered that most of the gold lost in the process of extraction 

 was lost from its connection with pyrites, and therefore that the results of Mr. Heale's 

 plan would be nil. He believed that twenty-five per cent, of the entire quantity of gold 

 in the quartz was lost from this cause. 



Mr. Heale did not believe that so large a proportion of gold was lost at the Thames, 

 except under special conditions ; his impression was that with the general run of stuff the 

 gold was extracted fairly, perhaps not perfectly. It was at times difficult to ascertain 



