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��SCIENCE.
��339
��the common gurnard (Prionotus caroliDua). The specimens having been drowned, the lungs were filled with water. The flahermen state that this species cannot remain under wnter more than Tour or five minutes.
The color of the back in the specimens se- cured was a light plumbeous tint. It shaded rather suddealy at the middle of ibe sides into the pure white of the under parts. I was informed that the depth of the color of the back varied considerably in different speci-
��Much butter is now made without any aalt at all, and the use of each butter is rapidly in- creasing. Salt is cheaper than butter, and there is therefore a tendency to use it to the maximum endurable by the eater. But butter without salt will hold more water ; and, as soon as this fact is generally known, aweet, moist butter will be more common than the dry, salt article. It would be a good thing if all the caseine could be washed out of the butter, but this is impracticable. Albuminous bodies
���mens, and it deepens very rapidly as soon as life is extinct, especially if the specimens lie in the aun, FREoEitiCK W. Trite.
NnUgual muBenin. Wuhintton.
��r BUTTER.
The work of the U. S. bureau of agricultural chemistry shows that the percentage of water in a gooil butter should not exceed twelve. In thirty-four analyses the highest percentage of water found was 14..')] , and the lowest 7.3i. It is naturally in the interest of the seller to incorporate as much water as possible in the butter. But, if alt butter should be legally condemned which should contain more than ten per cent water, the tendency to ' under- work ' the butler would be speedily corrected. In one instance a report of an analysis of foreign butter gave a percentage of water of 35.1*2. The quantity of salt in a butlershould depend solely on the taste of the consumer. I doubt very much whether the addition of a few per cent of salt helps preserve the butter. It is therefore a condiment only. In eighty- tour analyses the highest percentage of salt found was 6.15, and the lowest 1 .08. Two per cent is a fair mean of the salt usually present.
��decay more easily than all others, and butter with a great deal of card in it is very hard to keep sweet. Of all the conatitueuts of bnlter. this is the most difficult to estimate. Oleo- margarine butters contain no curd, unless they have been churned with milk, and even then not a great deal. If bntters do not have more than one per cent of curd, they may be accepted as having been properly prepared. Owing to the difficulty of estimating it, however, the quantity present should not be taken as a test of purity.
The fat of genuine butter is heavier than that of tallow. lard, or any of the common fats used as butter adulterants. Its specific gravity is about 912, water at the same tem- perature being taken at 1,000. The relative weight of tallow or lard often falls below 900. In analyses of commercial oleomargarine 1 have found the highest density to be 905. Of butter-fats in thirty analyses the maximum was 912.5. and the minimum 908.6. There should be grave doubt of the purity of a butter, if the specific gravity of the fat should fall below 909, For this reason the specific gravity of a butter-fat, if it be properly taken, is almost a certain test of its genuineness. The process is, however, a tedious one, and requires the greatest care and delicacy in manipulation.
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