April 24, 1885. J 



SCIENCE. 



339 



the common gurnard (Prionotus carolinus). 

 The specimens having been drowned, the lungs 

 were filled with water. The fishermen state 

 that this species cannot remain under water 

 more than four or five minutes. 



The color of the back in the specimens se- 

 cured was a light plumbeous tint. It shaded 

 rather suddenly at the middle of the sides into 

 the pure white of the under parts. I was 

 informed that the depth of the color of the 

 back varied considerabl}' in different speci- 



Much butter is now made without any salt at 

 all, and the use of such 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, sweet, 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 



■ 



THE BOTTLE-NOSE DOLPHIN, TURSIOPS TURSIO (AFTER FLOWER). 



mens, and it deepens very rapidly as soon as 

 life is extinct, especial^ if the specimens lie 

 in the sun. Frederick W. True. 



National museum, Washington. 



BUTTER. 



The work of the U. S. bureau of agricultural 

 chemistry shows that the percentage of water 

 in a good butter should not exceed twelve. 

 In thirty-four analyses the highest percentage 

 of water found was 14.51, and the lowest 7.34. 

 It is naturally in the interest of the seller to 

 incorporate as much water as possible in the 

 butter. But, if all butter should be legally 

 condemned which should contain more than 

 ten per cent water, the tendency to ' under- 

 work ' the butter would be speedily corrected. 

 In one instance a report of an analysis of 

 foreign butter gave a percentage of water of 

 35.12. The quantity of salt in a butter should 

 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- 

 four 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 curd in it is very hard to 

 keep sweet. Of all the constituents of butter, 

 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 butters 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 

 quant^ 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 I 

 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 purit} r 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. 



