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Stewart (Annual Report of the Pennsylvania State College for 1908-1909) gives a brief history of the lime-sulfur solution, its properties, preparation and use. He recommends 50 pounds burned lime, 100 pounds sulphur and 50 gallons of water boiled for 50 minutes. He advises that this solution be diluted to 1.03 Sp. G. for San Jose scale, and to as low as 1.003 Sp. G. for a summer spray on peach trees and suggests that the effectiveness may be due to the polysulphides acting directly or indirectly and to the free lime.

Van Slyke, Bosworth and Hedges, (New York Expt. Station Bull. No. 329) recommend 36 pounds pure burned lime, 80 pounds high-grade sulphur and 50 gallons water boiled for one hour. These authors consider that the fresh solutions contain only calcium thiosulphate and two polysulphides of calcium, the tetra and pentasulphides. No mention is made of the possible presence of calcium as the soluble hydrate, nor of hydrosulphide. They calculate the amount of calcium, combined as sulphides, from the total amount of calcium minus that present as thiosulphate, and from the amount of calcium obtained in this manner and the amount of sulphur present as sulphides, calculate the proportion of monosulphide to polysulphides. This would be accurate if the sulphur and calcium were present only as the thiosulphate and polysulphides. It was assumed however.

The effectiveness of the solution they claim depends directly or indirectly upon the amount of sulphides present in the solution. These authors recommend that the solution be diluted to a Sp. G. of 1.033 for San Jose scale and to 1.007 Sp. G. for summer spray.

Thatcher (Washington Experiment Station Bull. No. 76) gives a formula of 30 pounds lime, 55 pounds sulphur and boiled until all goes into solution. He considers that calcium pentasulphide and thiosulphate compose the greater part of the solution, while free calcium hydrate exists to some extent in solution and that a large excess of milk of lime was an advantage for marking purposes. The same ideas as to effectiveness prevail as in Haywood's work.

Giboney (Circular No. 1 Virginia State Crop Commission) considers 40 minutes boiling is enough and longer boiling causes the formation of lower sulphides. He also notes that magnesian limes have a deleterious effect on the composition of the solution.

Wellington (Bulletin No. 116, Mass. Station) claims that limesulphur contains 25 to 30 per cent of calcium monosulphide and hydrosulphide collectively. He in collaboration with Fernald showed that calcium thiosulphate possesses some insecticidal value. Whether it acts directly or indirectly is uncertain.

Tartar and Bradley (Jour. Ind. and Eng. Chem. Vol. II, page 271) consider that calcium tetra and pentasulphides are the chief constituents of lime-sulphur. Also that free calcium hydrate and hydrosulphide are not present. Their methods, however, are not refined enough to prove this.

"Harris (Technical Bulletin No. 6, Michigan Experiment Station) gives analyses of lime-sulphur solutions that are accurate on lime-sulphur solutions containing only polysulphides and thiosulphates. The presence of calcium hydrate and calcium hydrosul

phide would vitiate any results for mono-sulphide when calculated from iodine or acid titrations unless corrections were made for the effect of calcium hydrosulphide and calcium hydrate on the titrations. Harris assumed the absence of calcium hydrosulphide and calcium hydroxide in his work. He also shows that the composition of lime-sulphur is affected by high magnesia limes."

Shafer (Technical Bull. No. 11, Michigan Expt. Station) advances the theory that the lime-sulfur forms a sort of capsule about the scale and loosens the gum around the edges, and then, by oxidation of the lime-sulfur solution, the insect is deprived of oxygen and suffocates.

Many conflicating field experiments with this complex solution by horticulturists and entomologists have been reported, and probably will continue to be until the fundamental facts are ascertained. We believe from our analyses and others that lime-sulphur varies in the proportion of one ingredient to the other when prepared under even slightly varying conditions. Then any exact method of dilution of lime-sulphur solutions in general using specific gravity as a basis, would be erroneous. And again no one knows just what compounds possess the fungicidal value nor what dilution should be used to accomplish its purpose without injury to the foliage or whether the ingredient causing the injury is the one responsible for the fungicidal value. Also, climatic conditions seem to influence its action considerably according to some experimenters.

From the nature of the reactions that might take place on heating lime, sulphur and water together, one would naturally expect the resultant solution to be more complex than most of the analyses. made have appeared to indicate. With this idea in mind, the writers have attempted, by the use of more accurate methods, to determine these compounds directly, hoping thus to explain some of the discordant results heretofore reported. An attempt has also been made to prepare these compounds in a pure form for the purpose of ascertaining by actual trial to which of these the insecticidal or fungicidal properties are due, as well as the burning effect often noted when used as a summer spray, and also the proper strengths to employ.

We have been able to prepare pure solutions of calcium hydrosulphide by passing hydrogen sulphide through milk of lime, filtering, and supersaturating with hydrogen sulphide and then boiling off the excess of hydrogen sulphide. These solutions contained no free lime, no thiosulphate and no polysulphides. This hydrosulphide solution when boiled with an excess of sulphur gave a solution containing only calcium pentasulphide with no thiosulphates, no free lime or any other polysulphides. The successful preparation of these solutions requires close attention to details. Pure calcium. thiosulphate and lime water are easily prepared.

By our improved methods of analysis, which will be published at no distant date, we have demonstrated that free lime exists in all commercially boiled lime-sulphur solutions so far analyzed, varying with the method of preparation from minute quantities to 100 milligrams per 100 cc. solution; this is practically the same amount

as contained in a saturated solution of lime water. As is well known the thiosulphate varies considerably by different methods of preparation. The presence of hydrosulphide has been conclusively demonstrated, usually in small quantities it is true, but enough has been found to vary the proportions of monosulphide to polysulphide in nearly all cases. It is usually calculated as monosulphide and again as polysulphides and unless a correction is made on both, the proportion of monosulphides to polysulphides is incorrect.

Analyses of a boiled lime-sulphur solution by the new and improved methods which correct for the influence of lime and hydrosulphide in comparison with analyses by the methods commonly in use, give the following results expressed in milligrams per ec.

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Calculating the calcium not combined as thiosulphate as in combination with sulphides only, one would find the ratio of monosulphide to polysulphide 1 to 4.37 in the above solution. This method of calculating the amounts of tetra and pentasulphide has been used to quite an extent in the past.

From our studies of self-boiled lime-sulphur prepared and diluted carefully, we find that there is a wide range of variation in the final product more especially in strengths of the filtered solutions prepared at different times in the same manner. Eleven batches of self-boiled lime-sulphur were carefully prepared, using 16 pounds burned lime, 16 pounds sulphur, and finally diluted to 100 gallons with water. The results of the analyses of these solutions will be found in the following table.

WEIGHT IN MILLIGRAMS IN 100 CC. ORIGINAL SOLUTION.

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Calcium as

free lime

It will be noticed that the thiosulphate sulphur varied from 8 milligrams to 67 in 100 cc. of the solution and the sulphide sulphur from 7 milligrams to 227 in 100 cc. of the solution. These analyses were made primarily to ascertain the approximate dilution of commercially-boiled lime-sulphur when used as a summer spray. Since the self-boiled solutions varied so erratically hardly any guide as to dilution was found. At the time these samples were taken our method for determining free lime directly had not been developed. Since that time, however, we have worked out a reliable method for the determination of free calcium hydrate in the lime-sulphur solution and estimated the free lime in two self-bodied solutions prepared in the laboratory. These solutions contained 93.2 and 82.5 milligrams per 100 cc. respectively of calcium, present as free calcium hydrate. The sulphides were present in the proportion of 1 of monosulphide to 4.8 of polysulphides.

The only appreciable chemical difference that we have been able to observe between self-boiled and the diluted commercially-boiled lime-sulphur is in the amount of free calcium hydrate, the former containing an amount practically equal to that in a saturated solution of lime water while the amount in the diluted commercial product is nearly negligible.

In view of these facts it seemed to the writers that a commercially-boiled lime-sulphur solution diluted properly with lime water ought to give equally as satisfactory results as the self-boiled. Therefore, we diluted a commercial lime sulphur to different strengths and applied to peach trees as a summer spray. None of these solutions caused any injury, although one of the solutions contained five times as much polysulphide sulphur as did the strongest self-boiled solution in the preceding table (solution number eleven). While these field experiments were only preliminary to more extensive ones planned for the future we believe that they point to the possibility of using commercially-boiled lime-sulphur solutions diluted with lime water. While we deem it to be an advantage to dilute with a saturated solution of lime water, the result no doubt could be accomplished by adding one pound of burned lime to 100 gallons diluted commercial lime-sulphur solution. This is sufficient to saturate the solution, although an excess would make it more nearly comparable to a self-boiled solution and the undissolved calcium. hydrate would serve as a marker. If this should prove as efficient and safe as the self-boiled, it will be possible to more accurately control the strength of the spray and also to do away with the laborious and dirty process of making the self-boiled solution.

PROFESSOR MCCUE: One of the particular points brought out in this paper is that in regard to the so-called free sulphur. The paper has brought out that the injurious effects of the diluted commercial lime-sulphur may possibly be due to the hydrosulphide present, something that has not been taken into consideration heretofore. The paper also brought out the point that the difference between commercial-boiled and self-boiled lime-sulphur lies chiefly in the proportion of free lime present.

PROFESSOR FLETCHER: To what extent is that material used on peaches?

PROFESSOR WHITTIER: Professor McCue has used some of it on peaches and the chemical department did a little work with it, but it was so late in the spring when we got this idea, that we didn't have time to use it much, and, as I said, I feel the experiments were only to be considered preliminary. While we had a solution of commercial-boiled diluted with lime water but still five times as strong as our self-boiled solution and put it on the trees, it did no permanent harm. It is an easy method of spraying peach trees.

A MEMBER: In regard to the self-boiled lime-sulphur, is not there free sulphur in addition to the solution?

PROFESSOR WHITTIER: That is true.

A MEMBER: Would that have some value?

PROFESSOR WHITTIER: I will say in regard to that, that when you self-boil a solution, it brings the undissolved sulphur into a state probably similar to atomic sulphur and our experiments are going to be extended to include atomatic sulphur and also sulphur given off as free sulphur by oxidation of the commercial such as we have in the self-boiled to start with. This may be injurious or not, evidently nobody knows because the experts cannot agree. That is the reason so many chemists analyzing this product do not come to the same conclusions and do not agree. They practically admit by their conflicting analyses that they don't know any more about it than you do and couldn't say whether it is that sulphur or some other form of sulphur that burns or is useful.

PROFESSOR MCCUE: In connection with foliage injury, Thompson applied pure diluted hydrosulphide to the foliage of several trees and it took the foliage off.

PROFESSOR BLAKE: I think it has been shown by a number of experiments that very fine sulphur will control peach scab, if a sufficient amount is kept on the foliage. That has been shown by the Bureau of Plant Industry and in tests where sulphur has been applied as a dust spray, but results appear to show that dry sulphur is not as effective in controlling brown rot as sulphur in the selfboiled lime-sulphur form.

FRIDAY, NOVEMBER 21, 9.30 A. M.

PRESIDENT HEDRICK: The meeting will please come to order. The first paper this morning is "Characteristics of One Hundred Seedlings of the Northern Spy Apple," by Professor Macoun.

CHARACTERISTICS OF ONE HUNDRED SEEDLINGS OF THE NORTHERN SPY APPLE.

BY W. T. MACOUN, Central Experimental Farm, Ottawa, Canada.

At the Central Experimental Farm at Ottawa, Canada, seeds of a number of varieties of apples including Northern Spy were saved from the 1898 crop of fruit, the object being to obtain if

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