Observations on Liehigh " Organic Chemistry." 143 



bark, it would appear that humate of lime was then formed. Dr. 

 Madden [Qiiarterly Journal of Agriculture^ No. xlv., p. 90. and 

 91.) makes its components 28 of lime to 318^ of humic acid; 

 and humic acid contains 58 per cent of carbon : he thinks 

 humate of lime is gradually formed in the soil. Dr. Liebig is 

 of a contrary opinion. It will depend partly on whether the 

 humic acid has more affinity for lime than the carbonic acid. 

 Carbonate of lime is reckoned insoluble in water; humate of 

 lime, Dr. Liebig says, is no more soluble than the acid. It 

 would appear, also, he thinks, that humate of potash and soda is 

 not more soluble, which differs from most other combinations 

 of potash and soda; they generally form more soluble sub- 

 stances with the acids than before neutralisation : it would appear 

 that Dr. Madden thinks them more soluble. Some future 

 analysis may give more certainty on these points, and experi- 

 ments might be made on quicklime and moss water. As the 

 acid is only gjoo P^''^ ^^ ^^^ water, and 1 part only of lime 

 combines with between 11 and 12 parts of the acid, much lime 

 will not be needed in the process ; and, after being some time 

 mixed, the water may be evaporated : any humate of lime 

 formed will be of a brown colour. Lime, in its caustic or quick 

 state, is soluble in water, and. Sir H. Davy says, poisonous. 

 Being a substance not generally assimilated in the plant, it will 

 be poisonous if in excess ; so are soapsuds, though a manure ; 

 and so were sugar and starch, when Sir H. Davy applied them in 

 a concentrated state. But great quantities of lime-water are 

 applied regularly by gardeners to kill vermin ; it is reckoned 

 the least hurtful to plants of all the substances employed to kill 

 insects : 1 have used it in great quantity, and never saw it kill 

 a plant yet. Sir H. Davy says, limestone containing magnesia 

 is hurtful, because the magnesia after burning does not regain 

 its carbonic acid so quickly as the lime, and remains longer in 

 a caustic soluble state ; the lime regaining its carbonic acid 

 quickly is the reason, he says, why the caustic soluble lime does 

 not so often do harm, as it is neutralised before reaching the 

 fibres when put on in small quantities of lime-water, or when 

 washed slowly into the soil by rain. Magnesian limestone, he 

 says, is generally brown or pale yellow. When vitriol is poured 

 on lime, sulphate of lime, or gypsum, is formed, which, as before 

 stated, is valuable as a manure. Vitriolic matter is found in 

 peat soils. Some minerals contain a good deal of sulphur. 

 Gypsum and sulphate of potash are formed where sulphuric 

 acid and these bases are found ; and clover, being fond of sul- 

 phate of lime, is found to spring, as it were, naturally in such 

 soils. Clover is said to assimilate sulphate of lime as a con- 

 stituent. Soda in the state of sea salt is soluble, but acts as a 

 poison when taken in any quantity. Sir PI. Davy thinks it may 



