140 



KNOWLEDGE 



[June 1, 1898. 



Flo. 1. — From the under 

 side. X 120 diameters. 

 After Bersch. 



At first the acetic 



on every part of the acetifiers, and which finally had 

 brought the manufacture to a complete standstill — the 

 manufacturer being unable to account for their presence 

 beyond stating that they were derived from the soil beneath 

 his apparatus. 



In its simplest form an acetifier consists of a large vat 

 with a perforated false bottom. The space above this 

 is filled with shavings or other porous material on which 

 the bacteria settle, and the alcoholic liquid is pumped over 

 and over through the shavings until the whole of the 

 alcohol has been converted into acetic acid. The necessary 

 air is admitted through holes made in the side of the vat, 

 whilst smaller holes at the top allow the waste air to escape. 

 Many modifications of this apparatus are in use, in which 

 means are taken to exactly regulate the air supply and 

 the temperature ; but it is in this simple form, as first 

 invented by Sehiitzenbach in 1823, that most of the 

 acetifiers in England and Germany are constructed. Prior 

 to Schiitzenbach's invention, which 

 is still known as the " quick vinegar 

 process," vinegar was made by 

 placing the alcoholic liquid with a 

 little vinegar containing the bacteria 

 in barrels, which were turned and 

 aiirated from day to day by work- 

 men. It is through the holes for 

 aurating the acetifier that the 

 vinegar mite finds its way into the 

 interior, and attempts have been 

 made to prevent this by placing 

 birdlime round the outside of the 

 holes, whilst in some of the more 

 recent patents fine wire gauze 

 is employed for the same purpose 

 bacteria do not appear to be much affected by the presence 

 of the mites, but as these increase and then die ofl' and fall 

 to the bottom their dead bodies begin to putrefy, and the 

 putrefaction bacteria or their products sooner or later have 

 an injurious effect, and if not removed will eventually 

 completely master the acetic bacteria. 



The vinegar in which the mites have thus gained the 

 upper hand has a peculiar 

 yellowish shade, and con- 

 tains what appear to the 

 naked eye to be a large 

 number of white specks. 

 When examined under the 

 microscope these have the 

 appearance shown in Figs. 1 

 and 2. 



These two forms, appa- 

 rently those of the male and 

 female, are always found, 

 many of the individuals 

 being only one quarter or 

 one half of the size of the 

 others. Bersch assigns 

 them to the class of Sarcop- 

 tidce, but little appears to be known about their life history. 

 When once vinegar mites have established themselves 

 within an acetifier they can only be expelled by destroying 

 them simultaneously with the acetic bacteria. For this 

 purpose the vat must be emptied of vinegar as completely 

 as possible, and the interior thoroughly washed with hot 

 water, well fumigated with burning sulphur until all Ufe 

 is destroyed, and then washed again. It is then charged 

 afresh with the alcoholic liquid and a little crude vinegar 

 containing the bacteria, but of course it is some time 

 before the apparatus gets into working condition again. 



FiQ. 2 



; 120 diameters. 

 Bersch. 



A CLASSIC LEGACY OF AGRICULTURE. 



By John Mills. 



ALL great discoveries are the result of much study, 

 and often arise out of those truths of science which 

 appeared least promising on their first announce- 

 ment. The time is past when practice can go on in 

 the blind and vain confidence of a shallow em- 

 piricism, severed from science like a tree from its roots. 

 Scientific principles are now extensively applied in problems 

 concerned with the improvement of the artificial means em- 

 ployed for increasing the fertility of the soil. During the 

 last sixty years, more especially, the transmuting power of 

 the " philosopher's stone " has been displayed, and many 

 triumphs have been achieved through the painstaking re- 

 searches of men who, like Sir John Lawes and Sir Henry 

 Gilbert, are not content to adhere strictly to the role-of- 

 thumb methods which have been in vogue for untold ages. 

 Agriculture is both an art and a science. On the 

 scientific side chemistry plays an important part, and is 

 called into request for the investigation of the composition 

 of soils, manures, and of the vegetable and animal sub- 

 stances which it is the aim of agriculture to produce. All 

 the conditions of the life of vegetables, the origin of their 

 elements, and the sources of nourishment, are secrets which 

 can be elicited by the aid of science. Given a barren tract 

 of country, which has been unproductive from generation 

 to generation, the scientific agriculturist will improve the 

 parts by transporting and transposing the different soils. 

 The analysis of the soils will be followed by that of the 

 waters which rise or flow through them, by which means 

 he will discover those proper for irrigation. A knowledge 

 of chemistry teaches us when and in what condition to 

 use lime, and the difference in the properties of marl, peat, 

 dimg, mud, ashes, alkali, salt, soap-waste, sea-water, etc., 

 and consequently which to prefer in all varieties of soil— 

 a knowledge which thus imparts a new character to the 

 agriculturist, and renders his emploj'ment rational. 

 Environed by an endless variety of processes and results, 

 scientific agriculture is constantly disclosing surprises. 

 The nineteenth century has witnessed developments greater 

 than those of all previous time. It is as true to say now 

 that agriculture is in a state of transition and development 

 as it was a century ago to say it was in a state of inanition 

 and even stagnation. The position of agriculture is now 

 hopeful, for the age is progressive. It is a period of 

 adaptation, of new departures, new energy, and greater 

 economy. Foreign competition is understood and expected. 

 To know what it is provides the means of meeting it. 



We purpose m this article to afford a glimpse of the 

 artificial aids to agriculture which Sir John Lawes and 

 Sir Henry Gilbert have for upwards of fifty years practised 

 at the Rothamsted Agricultural Experimental Station — 

 the model of all agricultural stations, and the methods 

 there introduced are everywhere regarded as classical. The 

 researches carried on by these coUaborators have elicited 

 information which will ever serve as the foundation of a 

 truly scientific knowledge of the correlation of plant- 

 growth and manurial constituents of the soil, and will be 

 of the utmost value in all discussions of the chemistry of 

 plant Ufe. The immense number of exact data which they 

 have placed at the disposal of chemists is without parallel 

 in the annals of science. As Sir Joseph Hooker has said, 

 in the whole history of science, never have two of its 

 greatest divisions been brought into more profitable cor- 



• We are much indebted to both Sir John Lawes, Bart., f.b.s., 

 and Sir Henry Gilbert, f.e.s., for generous assistance in explaining 

 the arrangement of the experimental plots at Rothamsted, the 

 conduct of the laboratory, and in placing records, etc., at our disposal 

 in preparing this article. 



