Chapter 11

Dried wine grapes are prepared in a similar manner to raisins; that is they are dried in the sun, but do not require the same care in handling that are given to raisins. Wooden trays 2 × 3 are sometimes used, but it is by no means necessary to go to the expense of procuring trays, as it has been found that a good quality of coarse brown paper will answer every purpose, and this, with care, may be made to last two or three seasons. The drying was last season principally done on the bare ground, but there is much loss by shelling, as those dried are required to be turned; a pitchfork is used for that purpose. Brown building paper can be procured of city paper dealers in large rolls at four and a half cents per pound; according to the thickness, it will cost from one and three-quarters to three and a half cents per square yard. A thin, tough, waterproof paper is also made in rolls at about six cents a square yard. Wine grapes dry in from ten days to three weeks, according to variety and weather, and with the exception of Malvoisie, Rose of Peru, and Black Hamburg, from three and a half to four and a half tons of the green fruit are required to make one of the dried; these three varieties, however, being large, meaty, and a firm pulp, do not require more than from three to three and a half tons of the green fruit to produce one ton of dried, and are, therefore, the most profitable for drying; they also command better values in the market. The grapes are sufficiently dried when, on being rolled between the thumb and finger, no moisture exudes, and also when the stems are found to be dry and brittle, so that they can be separated readily from the berries. After the grapes have reached the proper state of dryness, they are taken in boxes or sacks to the packing house, where they are stemmed and cleaned, after which they are packed in white cotton sacks, holding from fifty to seventy-five pounds each, and when marked are ready for shipment.

The stemming and cleaning of the dried grapes is done by special machines designed for that purpose, which leaves the fruit in a bright, clean condition attractive to purchasers. These machines are at present built only by James Porteous, Fresno, and are operated either by hand or power. The cost of a stemmer and cleaner complete is $80, f. o. b. cars at Fresno. Where several producers can do so, it would be advisable to club together and get the machine in this way. Much extra expense could be avoided and one set of machinery would serve several vineyards, possibly an entire district where time was not a great object; or some one person in a district could purchase an outfit and do the work by contract, going from place to place. The capacity of the stemmer and cleaner is from five to eight tons per day, when the grapes are in proper condition; and the cost or charge for stemming, cleaning, sacking, and sewing up the sacks is from four to five dollars per ton when the producer furnishes the sacks. Good cotton sacks, holding about seventy-five pounds, cost from eight to ten cents each, including the necessary twine. Last year dried grapes were generally sold for cash, f. o. b., but it is probable that other markets could be secured by selling on consignment.

As to the advisability of such a course, each producer must himself be the judge. It is, however, quite certain that until consumers have an opportunity to try this product, the sales will necessarily be more or less limited, unless vigorously pushed by merchants and others interested in extending the markets for California products in the Eastern cities not yet tried. The varieties most suitable and profitable for drying, and especially for consumption in the Eastern markets, are the Malvoisie, Rose of Peru, Black Hamburg, Mission, Zinfandel, Charbono, Grenache, and in some localities the Carignan, of the dark varieties, and the Feher Zagos and Golden Chasselas of the white grapes; there are many other white grapes that are excellent when dried, but are too valuable for wine-making purposes, or are too small or deficient in sugar for use as dried grapes.

The same is true of the dark grapes, some of which ripen so late that it would be impossible to dry them in the sun, and the use of artificial heat is, at present prices, too expensive. Therefore, the varieties mentioned, which generally mature early, are found to be the most suitable for this purpose. This product is sold by dealers in the Eastern cities for cooking purposes, and as a substitute for dried fruits, such as peaches, apples, apricots, etc., in comparison with which it is usually much cheaper; while for stewing and for puddings and pies it answers the same purpose. The demand for this product will probably be gauged by the Eastern fruit crop; that is, the quantity that can be disposed of will depend upon the quantity of Eastern fruit in the market, and the prices will be largely dependent upon that of dried fruit.

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WALNUT OIL.

By THOMAS T. P. BRUCE WARREN.

This oil, which I obtained from the fully ripened nut of the _Jugluns regia_, has so many excellent properties, especially for mixing with artists' colors for fine art work, that I am surprised at the small amount of information available on this interesting oil.

Walnut oil is largely used for adulterating olive oil, and to compensate for its high iodine absorption it is mixed with pure lard oil olein, which also retards the thickening effect due to oxidation. The marc left on expression of the oil is said to be largely used in the manufacture of chocolate. Many people, I am told, prefer walnut oil to olive oil for cooking purposes.

The value of this oil for out-door work has been given me by a friend who used it for painting the verandas and jalousies of his house (near Como, Italy) some twenty years ago, and which have not required painting since. In this country, at least, walnut oil is beyond the reach of the general painter, and I do not know that the pure oil is to be obtained as a commercial article, even on a small scale.

It was in examining the properties of this and other oils, used as adulterants of olive oil, that I was obliged to prepare them so as to be sure of getting them in a reliable condition as regards purity. The walnuts were harvested in the autumn of 1887, and kept in a dry airy room until the following March. The kernels had shrunk up and contracted a disagreeable acrid taste, so familiar with old olive oil in which this has been used as an adulterant. Most oxidized oils, especially cotton seed oil, reveal a similar acrid taste, but walnut oil has, in addition, an unmistakable increase in viscosity. The nuts were opened and the kernels thrown into warm water, so as to loosen the epidermis; they were then rubbed in a coarse towel, so as to blanch them. The decorticated nuts were wiped dry and rubbed to a smooth paste in a marble mortar. The paste was first digested in CS2, then placed in a percolator and exhausted with the same solvent, which was evaporated off. The yield of oil was small, but probably, if the nuts had been left to fully ripen on the trees without knocking them off, the yield might have been greater. It is by no means improbable that oxidation may have rendered a portion of the oil insoluble. The decorticated kernels gave a perfectly sweet, inodorous, and almost colorless oil, which rapidly thickens to an almost colorless, transparent, and perfectly elastic skin or film, which does not darken or crack easily by age. These are properties which, for fine art painting, might be of great value in preserving the tinctorial purity and freshness of pigments.

Sulphur chloride gives a perfectly white product with the fresh oil, but, when oxidized, the product is very dark, almost black. The iodine absorption of the fresh oil thus obtained is very high, but falls rapidly by oxidation or blowing. A curious fact has been disclosed with reference to the oxidation of this and similar oils. If such an oil be mixed with lard oil, olive oil, or sperm oil, it thickens by oxidation, but is perfectly soluble. Such a mixture is largely used in weaving or spinning. Commercial samples of linseed oil, when cold-drawn, have a much higher iodine absorption, probably due to the same cause. Oils extracted by CS2 are very much higher than the same oils, especially if hot-pressed.--_Chem. News._

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THE PYRO DEVELOPER WITH METABISULPHITE OF POTASH.

By Dr. J. M. EDER.

Lately I called attention to the metabisulphite of potassium as an addition to the pyro solution for development, and can give now some of my experiences with this salt.

The metabisulphite of potassium, which was introduced into the market by Dr. Schuchardt, and whose correct analysis is not known yet, is a white crystal, which in a solid condition, as well as in an aqueous solution, has a strong smell of sulphurous acid. An aqueous 2 per cent. solution of this salt dissolves pyrogallic acid to a weak yellowish color, being distinguished from the more light brown solution of sulphite of soda and pyro. The solution kept very well for four weeks in half-filled bottles, and showed a better preservation than the usual solution of pyro and sulphite of soda. More than 2 per cent. of the metabisulphite of potassium is without any advantage. If this solution is mixed with soda, a picture will develop rapidly, but the same will show a strongly yellow coloration in the gelatine film. Sulphite of soda has to be added to the soda solution to obtain an agreeable brownish or black tone in the negatives.

If the contents of metabisulphite and pyro-soda developer are increased, it will act very slowly; larger quantities of the metabisulphite of potassium, therefore, act like a strong retarder. In small quantities there is no injurious retarding action, but it will have the effect that the plates obtain very clear shadows in this developer, and that the picture appears slower, and will strengthen more slowly. The strongly retarding action of larger quantities of metabisulphite might be accounted for in that the bisulphite will give, with the carbonate of soda, monosulphite and soda bicarbonate, which latter is not a strong enough alkali to develop the bromide of silver strongly with pyro. An increase of soda compensates this retarding action of the metabisulphite of potassium.

Good results were obtained by me with this salt after several tests, by producing the following solutions:

A.

Pyrogallic acid 4 grammes. Metabisulphite of potassium 1½ " Water 100 c. c.

This solution keeps for weeks in corked bottles.

B.

Crystallized soda 10 grammes. Neutral sulphite of soda 15 " Water 100 c. c.

Before using mix--

Pyro solution A 20 c. c. Soda solution B 20 " Water 20 "

The developer acts about one and a half times slower than the ordinary pyro soda developer, approaching to the latter pretty nearly, and gives to the negatives an agreeable color and softness, with clear shadows. If the negatives are to be thinner, more water, say 30 to 40 c. c., is taken. If denser, then the soda is increased, and the water in the developer is reduced. An alum bath before fixing is to be recommended.

An advantage of this development is the great durability of the pyro-meta sulphite solution. The cost price is about the same as that of the ordinary pyro developer. At all events, it is worth while to make further investigation with the metabisulphite of potassium, the same being also a good preservative for hydroquinone solutions.--_Photographische Correspondenz; Reported in the Photo. News._

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