254 



THE AGRICULTURAL NEWS. 



August 1. 1914. 



FUNGUS NOTES. 



fidiiL Uu-iie chfinical manufacturer!: 



( )rii;in. 



'ritf per Iti. 



PURCHASE AND USE OF LIVER OF 



SULPHUR. 



Liver of sulphur (potaswiuiu sulphide) is a \alua- 

 li''' fungicide for the treatment of mildew of vaiioiis 

 jilants and is used to replace Bordeaux mixture in 

 (circumstances where the spotting of leaves or fruit b}* 

 that fungicide renders its use undesirable. I'he results 

 obtained fi'om the use of liver of sulpliur ha\e some- 

 times been reported as very unsatisfactory, and it is 

 jjrobable that these failures are explained by the results 

 "if certain experiments madt in the labi>ratorv of the 

 -litish Board of Agriculture and reported in the 

 luraal of that body fir June 1!>14, ]i]). •23(i-41. 



Liver of sulphur, as .sold couiiuereially, i> a mixture i>f 



3rsl chemical compounds. It is obvious that its value as 



spraying material will depend njioii its eontent of such 



bstances as have a fungicidal arti'in; ami it is al.so clear 



'.'■lat the proportion of these sulistances jiresent might 



possibly vary according to the method of preparation of the 



liver of sulphur by the manufacturers and also according to 



the way in which the liver of suli)hur is stored sub.seijueut to 



juanufacture. as other compoiuuis may lie expected tci lie 



formed on exposure to the air. 



Foreman's experiments* with weak solutiims ui each of 

 the various compoiinds found in liver of sulpliur on the 

 germination of spores of Botri/tis Cinerea and Spliacratheca 

 'ni.f>rs-uvae appear to show that sidpliur in the form of 

 .sulphides (hyclro-sldphide, sulphide and ]ioiysulpliide) is the 

 valuable fungicidal agent in liver of suljihur. On this 

 assumption,! it has been shown, as the result of analyses 

 r-onducted at the Government Lalxiratory on behalf of the 

 iioard. that the efficiency of liver of sulphur may vary widely 

 pad that the term may mean anything from a worthless to 

 ft very valuable article. Some of the sam|)les analysed were 

 obtained by the Government Laboratory direct from large 

 chemical manufacturers, but the bulk were ])urchased for the 

 "Board in different parts of the country during ,lune and .July, 

 ttie .season in which liver of .nilphur is reijuired for spraying 

 purposes. The results of the anal_yses are all the more 

 interesting, since, owing to the divergence in the method of 

 jiacking the samples for dispatch to tlie Government Labor- 

 atory, the degree of exposure to the air differed greatly. To 

 lo.st the conclusions as to the effect of exposure due to 

 inefficient storage, investigations on the point were also 

 carried out at the Government Laboratory It will be 

 convenient, however, to consider first tlie variation due to 

 rlifference in the method of preparation. 



VARIATION ly CONTENT OF 'sULPHIHK' sr I. Cn I I; liCK To 

 DIFFERENCES IN THE METHOD OF I'l; KC U; A I To-<. 



The following were the results of tlie analyses of the 

 luples purchased by the Government Lalioratfiry direct 



■'■■" Jovriial of Agriculiural Science, Vol. Ill, page 400. 



t Apart from this, the proportion of 'sulphide' sulpliur 

 gives the best indication as to wliether liver of sulphiu- has been 

 prepared according t<i the usual method and is in a fresh 

 condition. 



Content of 'sulphide' 

 sulphur per cent. 



21 -.53 

 19-83 

 26-07 

 27-64 

 30-OS 

 23-.57 



These figures show fairly wide variation in 'suliihide' 

 sulphur content. 



In the case of the samples piu-chased for the Board 

 locally, taking only those samples which were dispatched 

 properly ]jacked in tins or liottles, the 'sulphide' sulphui 

 content of twelve samples was found to vary from 4-90 jjer 

 cent, to 37-94 per cent. Two of these samples contained 

 6-71 and 4'90 per cent, respectively of 'sulphide' sulphur, and 

 while one of these was insecurely closed, it is quite possible 

 tliat the other was 'weathered' before purchase. However, 

 the fact that the remaining ten samples varied from 2-5 to 3S 

 per cent, in content of 'sulphide' .sulphur (these ten .sampless 

 being all among those most nearly resembling freshly made 

 liver of sulphur) taken in conjunction with the results 

 obtained from the samples purchased direct from large chemi- 

 cal manufactui'ei's, makes the conclusion tolerably certain 

 that, as mamifacturetl, liver of sulphur varies widely in vahie. 



Although it is ])ossible that the results of the analysis of 

 sam]iles whicli were forwarded to the Government Laboratory 

 packed in paper have not the same value, the evidence 

 att'oi'ded by them corroliorates the above results. Thus the 

 'sulphide' sulphur content of twenty-three samples so dispatch- 

 ed varied from O-S,'^ per cent, to 31-44 per cent. 



The absence of any connexion between the pric;e and the 

 efficacy of the fungicide which is evident from the figures . 

 in the above table, was also found in the samjiles jjurchased 

 in ditt'ereut parts of the country, the prices of which varie(J 

 from r>d. to 4s. |ier Iti. 



V-AKI.ATION IN CONTENT OF 'SULPHIDE' SLLCHll; OLE Tc ► 

 DIFFERENCES IN METHOD OF STORAGE. 



Exposed to the air in a .solid foim liver of sulphur 

 ra])idly absorbs water and carbonic acid, turns from a liver 

 brown to a greenish yellow colour, and evolves suljihuretted 

 hydrogen. The change can be seen by breaking a lump of 

 the substance that has been exposed to the air. The face of 

 the fracture shows on the extreme outside a ring of greenish 

 grey colour, within this a band of yellow, and in the centre 

 the liver brown colour of the original substance. Exposed to- 

 the air for a hmger time, the whole of the substance becoine.s 

 of a grey cokiui', crundiles readily to a powder, and no longer 

 evolves sulphuretted hydrogen. When a solution of liver of 

 sulphur is allowed to stand in contact with the air, sulphui 

 soon begins to separate and gas is produced. These reactions 

 appear ultimately to convert the sulphides into sulphur, 

 carbonates, and sulphates. 



This effect of expo.sure to the air was actually found in 

 the analyses of the samples purchased for the Board locally, 

 the content of 'sulphide' sulphur varying, as already stated, 

 from 4-90 to 37-94 per cent, in the case of samples jiroperly 

 packed and from 0-88 per cent, to 31-44 per cent, in the case 

 of samples packed in paper. A complete statement of the 

 results of the analyses, however, gives a nuich better idea of) 

 the difference in the sulphide content in the two cases. 



