Artificial Fog

Immanuel Kant, Critique of Pure Reason, Introduction (1781) Safety Precautions 

A large amount of smoke is evolved during llie leacvion, wliidi must therefore be carried out either in the open air or in a well ventilated hood. Wear safety glasses KOH can cause severe damage to the skin or eyes, and in case of skin contact the area affected should be washed for at least 15 minutes under running w ater. The same applies for eye contact, but in this case a doctor should be consulted in addition. The toxicity of hydroxylammonium chloride is unknown, but there is a possibility that it is cancerogcnic. 

20 g of K( )l I and 20 g hydroxylammonium chloride are weighed out into the two 50 mL beakers. The two chemicals are then mixed rapidly and thoroughly in the tin can with the help ol a glass rod. Tlie read ion starts better when the mixture is formed into a heap in the reaction vessel. The reaction starts after about 30 seconds white smoke is evolved. 

The smoke consists mainly of water, ammonia, ammonium chloride and iiiiro-gen. However, its composition has still not been exactly determined, and it is possible that highly toxic compounds may be present in small amounts. 

The residue in the can should be dissolved in water, neutralised using dilute hydrochloric acid and poured down the drain. 

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How Do Fog Machines Create the Artificial Fog or Smoke Used in Theatrical Productions ... 

Whether for a dramatic scene or a science-fiction fantasy, the use of artificial fog to create ambience and special effects is commonplace in theatrical and film productions. On what basic chemical principles do fog machines operate ... 

Some of the most memorable scenes in a motion picture are the creation of special effects technicians. One standard tool in the entertainment industry to create ambience, simulate specific designs such as volcanoes or swamps, or accentuate optical effects is fog production. (In the theatrical sense, the terms fog and smoke are used interchangeably for mist consisting entirely of liquid droplets. In the chemical sense, fog refers to a liquid phase dispersed in a gas, while smoke contains solid particulate matter dispersed in a gas.) There are a variety of approaches to creating artificial fog or smoke. 

Figure 3.8.2 The molecular structure of propylene glycol, used in artificial fog machines.

How do fog machines create the artificial fog or smoke used in theatrical productions See p. 23. 

Quiney and Carswell (1972) made measurements on artificial fogs and reported that S33/Sn and 5 34/5 1, showed more pronounced differences from one fog to another than did the more commonly measured matrix elements such as Sl2/Su. Hunt and Huffman (1975) suggested the possibility of using S3A/Sll at a single angle near 95° to monitor the mean size of nebulized water droplets. Because little use has been made of all matrix elements, however, a systematic study of their relative merits in determining size distributions has not been made. 

Smoke formation an artificial fog is created by burning damp organic materials. A temperature rise of around 2-3°C can be achieved with organized smoking. 

Penkett, S. A. and Garland, J. A., 1974 Oxidation of sulphur dioxide in artificial fogs by ozone. Tellus 26, 284-290. 

In late 1915 or early 1916, Schmidt, a cousin of Friedrich Schmidt-Ott, " ministerial director and later Prussian Kultusminister (Minister of Education), contacted Fritz Haber, whose Kaiser Wilhelm Institute (henceforth KWI) for Physical Chemistry and Electrochemistry had from late 1914 been converted into a centre for chemical warfare research. Schmidt proposed the creation of a foundation with an endowment of 250,000 marks to reward persons who have rendered a scientific or technical service to the war effort and who can use it . Schmidt envisaged that Captain Haber would manage the foundation and propose suitable individuals for honours. The documents do not show whether Schmidt was thinking of himself, but he did belong to the circle of possible candidates. He had developed a tear gas, as well as a method to produce artificial fog (so-called Hochst fog ), which was used in the Battle of Jutland on 31 May 1916. 

In a salt spray test the sample is brought in contact with a saline fog in a closed chamber for a certain number of hours. The fog is formed by atomizing a NaCl solution by means of a nozzle. The high corrosivity of the artificial fog simulates that of a marine atmosphere, but the method does not offer a realistic model of more general atmospheric corrosion conditions, because it involves neither the presence of SO2 nor humidity cycling. In order to accelerate the corrosion, acetic acid or copper chloride is sometimes added to the saline solution. 

Early in 1942 the CWS produced smoke apparatus which met the necessary requirements, the Mi mechanical generator which created an artificial fog not by combustion but by the condensation of water and oil. Its principal drawback was its 3,ooo-poimd weight and its awkward size. The small, compact M2 model, which appeared in 1944, overcame both of these handicaps. 

The hierarchy may have to do also with the simple fact that the surface must be able to repel both macroscopic and microscopic drops. Experiments with artificial fog (microdrops) and artificial rain (large drops) show that surfaces with only one scale of roughness repel rain drops well. However, they cannot repel small fog drops which are trapped in the valleys between the bumps. ... 

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