384 THE POPULAR SCIENCE MONTHLY. 



thickness of half an inch. The mycoderm seems to have an oxidizing 

 action, and so, when the alcohol in the liquid fails, it probably grows 

 at the expense of the acetic acid, converting it to carbonic dioxide 

 and water. There is a popular notion that the presence of " mother " 

 shows that the vinegar is made from cider, and is of good quality, but 

 the vinegar-plant appears also in vinegar made from molasses, and it 

 is really as undesirable in vinegar as mold on bread. 



The little, wriggling creatures which swarm in some vinegars have 

 been credited by uneducated persons with being the "life" of the 

 vinegar. In one sense they are, but their presence is in no way bene- 

 ficial. These vinegar-eels (Anguillula aceti), as they are called, are 

 developed in most fruits, and hence readily find their way into vinegar 

 made from fruit-juices. Vinegar which contains them must contain 

 also as impurity some mucilaginous or albuminous matter, or the eels 

 would have no food and could not exist. They need air also, and they 

 have been observed engaged in a curious struggle with the mycoderm 

 on the surface. The plant tends to prevent their obtaining the requi- 

 site supply of air, and the eels were seen combining their efforts to 

 submerge it. They may be killed by heating the vinegar to 128° 

 Fahr., or by adding boracic acid. Vinegar when long kept, especially 

 if exposed to the air, putrefies and becomes ropy, losing its acidity, 

 and acquiring an unpleasant smell ; the presence of the vinegar-plant, 

 vinegar-eels, or other foreign substances, is liable to induce putrefac- 

 tion, especially if the vinegar is weak. 



THE WEEK OF SEVEN DAYS. 



Bt THE BISnOP OF CARLISLE. 



IF a being from another world, suddenly placed among us, should 

 examine terrestrial institutions, he could scarcely fail to inquire 

 why it is that in so large a portion of the earth time is measured by 

 periods of seven days. To a large number of persons among our- 

 selves such inquiry is practically superseded by the consideration that 

 the Bible opens with the recognition of the week : whatever discus- 

 sion may be raised, and whatever may be the demands of science 

 with reference to the interpretation of the commencement of the book 

 of Genesis, the fact remains that it is asserted that in six days God 

 created the heaven and the earth, and all things in them, and rested 

 on the seventh day. The same assertion i3 renewed by the fourth 

 commandment, which enjoins the keeping holy of the Sabbath-day. 

 And when we remember how thoroughly the sanctification of one 

 day in seven has been adopted and enforced by the practice of the 

 Christian Church, and how the first day has been marked, in virtue of 

 the chief article of Christian faith, as emphatically the Lord's Day, 



