TRANSACTIONS OF SECTION B. 505 



The simplest, and indeed the most reasonable, constitutional fonmila that can 

 be assigned to this new body, which may be termed monomercuric methylene iodide, 

 is I(CH.2)"HgI, the divalent radical methylene (CHo)", combining to the extent of 

 half of its power with iodine on the one hand, and to the same extent on the other, 

 with Hgl, which plays the part of a mouatomic radical. The novelty of the com- 

 pound is revealed in the fact just stated, inasmuch as all the so-called organo- 

 metallic bodies hitherto known are characterised by the monatomic nature of the 

 alcohol radicals which tliey contain, viz. methyl, ethyl, amj'l, and allyl. 



It has already been stated that two products are formed by the action of mer- 

 cury upon methylene iodide. This second compound has not yet been obtained in 

 the pure state. It was, however, analj'sed ; and from the results, as well as from 

 some of its reactions, there is reason to believe that this body is dimercuric methylene 

 iodide, CH,(HgI)o. 



The action of zinc, as well as of sodium amalgam in presence of acetic ether, 

 upon methylene iodide were tried, and tlie results of these experiments will be the 

 subject of a future paper. If the zinc compound be successfully isolated, it cannot 

 fail to be of great service in building up bodies of the homologous series, where 

 the consecutive members differ by CH,,, and we may thus be able to synthesise 

 higher alcohols by a comparatively simple process. 



5. On the Applicoilon of Organic Acids io the Examination of Minerals. 

 By Professor H. Caerington Bolton, Ph.D. 



The following research into the behaviour of the commoner minerals with or- 

 ganic acids was prompted by the dithculty of transporting the liquid mineral acids 

 on mineralogical and geological journeys. A careful study of the action of citric 

 acid on 200 mineral species has established the fact that this organic acid possesses 

 a power of decomposing minerals only slightly less than that of hydrochloric acid. 



The manner of conducting the investigation was briefly as follows : the mineral 

 to be examined was very finely pulverised, and treated in a test-tube with a satu- 

 rated solution of tlie organic acid in the cold, and then the contents were heated 

 to boiling. Preference is given to citric acid, because it appeai-s to have greater 

 decomposing power than either tartaric or oxalic, owing probably to the greater 

 solubility of metallic citrates. 



In order to increase the power of the organic acid, two other reagents have 

 been employed in connexion with it; these are sodium nitrate and potassium 

 iodide. These are added, in solid form, to saturated solutions of the citric acid at 

 the moment of using. 



Minerals belonging to several groups were submitted to these processes, and 

 gave phenomena which may be summarised as follows: — 



1st. More or less complete decomposition and solution of oxides, phosphates, &c., 

 without formation of precipitates or liberation of gases. 



2nd. Complete solution of carbonates, with liberation of carbonic anhydride. 



3rd. Decomposition of certain sulphides with evolution of sulphuretted hydrogen. 



4th. Decomposition of certain sulphides, with oxidation of the sulphur. 



5th. More or less perfect decomposition of silicates, with separation of either 

 slimy or gelatinous silica. 



6th. Decomposition of certahi species by reagents forming characteristic pre- 

 cipitates. 



7th. Wholly negative action. 



The exact lieha^iour of each species is shown in the annexed table. 



The application of this method of examining minerals to field work is obvious ; 

 and this newly developed power of organic acids has undoubtedly an important 

 bearing on the chemistry of geological changes. The quiet work of the organic 

 acids of the soil in decomposing rocks and minerals demands greater recognition 

 than is usually accorded. 



