Combustion Experiments with Flesh and Animal Fat

“While in the crematorium ovens [of Auschwitz], once corpses were thoroughly alight, it was possible to maintain a lasting red heat with the help of fans, in the pits the fire would burn only as long as the air could circulate freely in between the bodies. As the heap of bodies settled, no air was able to get in from outside. This meant that we stokers had to constantly pour oil or wood alcohol on the burning corpses, in addition to human fat, large quantities of which had collected and was boiling in the two collecting pans on either side of the pit. The sizzling fat was scooped out with buckets on a long curved rod and poured all over the pit causing flames to leap up amid much crackling and hissing.” [1]

1. Introduction

In the article entitled “Die Krematoriumsöfen von Auschwitz-Birkenau“[2] (The crematoria ovens of Auschwitz-Birkenau), which I wrote on the basis of the first results (1993) of a general study of cremation conducted with the precious help of Dr. Ing. Franco Deana, I dedicated section 6.2 to the problem of “Verbrennungsprozess in einer Grube” (combustion process in a pit).[3] In this section, I called the system of combustion in a pit technically inefficient for fundamental reasons, and judged the combustion system described by the witness Filip Müller[4] to be “wärmetechnisch unmöglich“ (thermo-technically impossible).

During further work after the publication of that article, I came across the important book “Die Kadaver-Vernichtungsanlagen“[5] (carcass disposal plants) written by German engineer Wilhelm Heepke who was one of the foremost German cremation specialists in the first four decades of the twentieth century and whose indisputable competence in this field I had already been able to appreciate while reading another of his fundamental works.[6]

Heepke's book contains a section entitled “Die Verbrennung in Gruben” (combustion in pits), which is of great interest in connection with the topic of the “cremation pits” at Birkenau.

After 1995, my documentation on Auschwitz increased considerably, making it necessary for the first version of the article to be completely revised; however, being able to make only general corrections to the English edition, I decided to drop the section on combustion process in a combustion pit entirely.[7] This topic required an individual treatment, which I can only now present to the public, after having dealt with the fundamental problem of the height of the ground water level at Birkenau.[8]

In the present article, I shall deal with the experimental data that will be used in a further paper covering specifically the topic of corpse incinerations in the open pits at Birkenau.

2. Carcass Burning in Pits According to W. Heepke

2.1. General Principles

Document 1: Sketch of a pit with iron grid for carcass combustion. (Click to enlarge)

Documents 2 & 3: Results of experiments of carcass combustion on iron grids conducted in 1902. (Click to enlarge)

2.2. “Kiln combustion”

Here, Heepke describes the “kiln combustion, as has been practiced for many years in Finland by the local chief veterinarian Fabritius,”[10] which, however, does not concern us here because such a method was never used at Birkenau.

2.3. Burning on an Iron Grid

Document 4: Experimental results of carcass incineration in cremation ovens. (Click to enlarge)

2.4. Practical Experience

2.5. Combustion Pits in Swampy Terrain

This aspect is without doubt the most interesting case to be examined in connection with our topic, as the Auschwitz-Birkenau camp was located in a heavily swampy area:[13]

Photographs 1-3: Structure of Mattogno's crematory oven.

The most important information resulting from these experiments is the fact that the pits, because of their shallow depth (0.75 meters), required the positioning of an iron windscreen all around them, 1 meter high. Without this, their efficiency would have been considerably lower because of higher heat losses. In pits unprotected by a screen, only one layer of fuel and one layer of carcasses could be placed.

3. Nature and Aims of the Experiments Described by W. Heepke

It can be seen from the experiments described by Heepke that the ratio of fuel to flesh is always less than one; in other words, the combustion of one kilogram of flesh requires less than one kilogram of fuel – more precisely, between 0.39 and 0.80 kilograms of wood. We have to state, though, that the aim of the experiments was only to render hygienically harmless the carcasses of animals that had died from infectious diseases; for this, a more or less complete carbonization was all that was required. That the result was not an incineration, i.e., a complete reduction of the carcass to ash, can be deduced from the fact that Heepke published a table reflecting the practical results of animal incinerators built by the H. Kori company of Berlin (see document 4). The results show that the largest type of equipment of this kind, oven 4b, was able to incinerate 900 kg of flesh in 121/2 hours using 300 kg of hard coal. This fuel has a heating value 2.5 times that of ordinary wood; hence, such an oven would have required as much or even more wood than a burning pit – which is obviously impossible.

For more reliable results, I conducted a number of experiments as described in the following sections.

4. Combustion Experiments by C. Mattogno
(October – November 1994 and February 1995)

4.1. Incineration Experiment in a Field-Type Crematorium Oven.

For the purposes of the experiments described in this article, I built a field-type oven from tuff blocks; photographs 1, 2, and 3 show its structure.

Measurements of the oven

• Total inner dimensions: width 27 cm; depth 60 cm; height 75 cm
• Combustion chamber: Height 27cm
• Hearth chamber: Height 39 cm
• Hearth grid: 27 cm × 53 cm, mesh spacing of 1×2 cm²
• Ash chamber: Height 13 cm.
• Combustion grid: longitudinal bars 1 cm apart (see photograph 2), placed 39 cm above the hearth grid.
• Effective surface of the grid: 50 cm × 27 cm = 1.350 cm²
• Chimney: internal cross section area 27 × 20 cm; height 70 cm from the ceiling of the combustion chamber, 97 cm from the grid of the combustion chamber.
• Device for closing the combustion chamber: 2 vertical blocks (see photograph 3).

The experiment was conducted with 6.5 kg beef (see photo 4).

Photo 4: Prepared Beef

Technical data

• composition of beef (6.5 kg): bones 3.0 kg; fat 1.0 kg; cartilage 0.2 kg; muscles flesh 0.6 kg; offal 1.7 kg
• temperature of meat: 19°C
• wood used: dry oak wood and pine branches
• start of the experiment: 15:45 hours

Results of the experiment

• duration: 1 hr 15 mins.
• ash from flesh: 0.65 kg (= 10% of initial weight) (see photo 7, large pan)
• total wood consumption: 17.1 kg
• wood ash: 0.45 kg (= 2.6% of initial weight), (see photograph 7, small pan)
• ratio fuel/flesh: 17.1/6.5 = 2.63 (the weight of fuel used was 2.63 times that of the incinerated flesh)

Observations

Operation of the oven: Initial fuel load 5.1 kg wood (one layer of wood 30 cm high, see photograph 5), later loads every six to seven minutes. Combustion occurred with the front opening of the combustion chamber closed by means of two blocks of tuff placed vertically and leaving the opening of the ash chamber free. Into this chamber I had placed two aluminum pans for the collection of ash.

Photo 5

Photo 6

Photo 7

Combustion process: The chimney smoked for only seven to eight minutes after lighting the fuel; thereafter, combustion became very intensive (see photograph 6), the fat started to melt rapidly, and after not more than 8 minutes tongues of flame appeared at the top of the chimney, reaching a height of some 30 cm; combustion was very intensive almost throughout the duration of the experiment, subsiding only towards the end. In the initial phase of the combustion, after about 10 minutes, small amounts of grease dripped into the pans in the ash chamber, igniting almost immediately.

Ash: The ash consisted of a few rather large pieces, some smaller ones, and many little splinters and minute fragments. The bone residues were mostly white, very porous and friable with small black portions; all the residues could be easily broken up with light finger pressure.

4.2. Experimental Incineration in an Open Furnace

Technical data:

• Oven: width 27 cm; depth 74 cm; distance hearth grid to combustion grid 23 cm.
• composition of beef (10.8 kg): bones and cartilage 4.1 kg; fat 2.1 kg; muscle flesh 1.9 kg, offal 2.7 kg
• temperature of meat: 17°C
• dry oak wood and pine branches
• start of experiment: 14:00 hours

Results of experiment:

• duration: 2 hr 40 mins
• ash from beef: 0.55 kg (= 5.1% of initial weight)
• wood consumption: 33.5 kg
• ash from wood: 0.85 kg (= 2.5% of initial weight)
• ratio fuel/flesh: 33.5/10.8 = 3.1 (the weight of the fuel used was 3.1 times the weight of the incinerated beef)

Observations:

For this experiment, the same grids were used as in the preceding one.

Operation of the furnace: initial fuel load was 4.5 kg with subsequent loads according to progress of combustion

Combustion process: the furnace smoked intensively for the first hour, the smoke being initially dark grey, later bluish, and eventually died down. Over the first hour, the wood burnt irregularly; light flames appeared over the flesh after 30 minutes. The fat, which ran into the pan of the ash chamber, caught fire immediately and burnt with a bright flame (see photograph 9, taken after 15 minutes). The flesh caught fire after one hour. After two hours, the flesh was still burning intensively. To overcome the frequent drops in intensity of the fire, I started to split the wood into thinner pieces after the first half hour. I often stoked the fire by means of a metal rod. I also frequently stoked the flesh and pushed it to the back of the combustion chamber as it dried out and burnt. Under the effect of the draft, the flames concentrated in the rear part of the furnace after the first half hour.

Odor: smell of burning flesh, not very intensive, during the whole duration of the experiment

Photo 8

Photo 9

Photo 10

Ash (see photograph 10): The ash was constituted of rather large bone fragments with a white appearance on the outside, but black on the inside; these residues were partly friable and partly rather hard.

At the end of the experiment, I measured the temperature of the embers (without flames) by means of an oven thermometer located at a height of 10 cm above them. For the first few minutes, the temperature remained at around 270°C.

4.3. Experiment of Burning in a Pit Excavated in the Ground (February 21, 1995)

Technical data

• pit measuring 0.85 by 0.50 by 0.60 (depth) meters (see photograph 11)
• beef (15 kg): mostly organs from the thoracic and the abdominal cavity (see photograph 12)
• fuel (52.5 kg): dry pine cones 1.5 kg; dry pine branches 3.0 kg; seasoned fire wood, oak, 40 to 60 long, 4-6 cm in diameter 48.0 kg; ethyl alcohol 1.5 liters
• temperature: 14°C
• start of experiment: 16:00 hours

Preparation of experiment

I laid out the pine cones on the bottom of the pit, covering them with the pine branches, upon which I piled the wood in a regular fashion, placing the logs alternately lengthwise and across to a height of a few centimeters above the ground. In this way, the wood constituted a kind of lattice with generous space for air circulation. The total weight of the wood was 42 kilograms.

I placed the flesh on the wood so as to cover little more than about half the surface area. I doused the wood with the alcohol and set it on fire.

Phases of the combustion process

The fire took rapidly and easily at the bottom (where the most easily inflammable material was placed) and then spread slowly upwards.

• lively combustion after 5 minutes
• intensive combustion after 25 minutes, flesh almost intact (see photograph 13)
• after 30 minutes, when the level of the wood had already dropped by about 20 centimeters, I distributed the rest of the wood (10.5 kg) in a regular fashion over the flesh
• bright flames leaping out of the pit after about 45 minutes (see photograph 14)
• combustion with short flames after 50 minutes
• combustion with short flames after 60 minutes, flesh residue still covered by wood and embers
• as the wood was being consumed, the residue of the flesh slowly became visible. Bright flames, dying down. Three thick pieces of carbonized flesh remaining on the glowing embers
• flames stopped after 1 hour and 35 minutes
• photograph 16 shows the remains after 1 hour and 45 minutes

Photo 11

Photo 12

Photo 13

Photo 14

Photo 15

Smoke: Weak generation of smoke upon lighting and for a few minutes thereafter. Later, as combustion intensified, the smoke died down considerably. Very little smoke from the flesh in the succeeding hours.

Odor: Odor of low intensity during the combustion process, non-nauseating, also later while the residue remained on the embers.

Air temperature in front of the pit: After about 50 minutes, I attached an oven thermometer to a metal rod, which I fixed in the ground in front of the pit; the rod was bent forward until the thermometer was situated above the edge of the pit at a height of 90 centimeters (see photograph 15). Maximum recorded temperature: 120°C. The level of the wood, which burnt with short flames, had dropped to about 40 cm below ground level.

Temperature of the embers: The experiment was started at 16 hours. Once the flames had stopped, I watched the pit until evening. The next day (February22) at 8 hours (air temperature 5°C) I introduced the tip of the thermometer rod into the embers and recorded the temperature every hour. At 8 hours (16 hours after lighting), the temperature of the embers was about 320°C; it stayed above 300°C until 13 hours. At 16 hours (24 hours after lighting) it was still 280°C. After stirring the embers with a metal rod, temperature rose to 340°C and stayed above 300°C for another 2 hours. At 23 hours (31 hours after lighting, the embers were still at 160°C.

Results

I recovered the ash (see photograph 17) the next morning (February 23). The results were as follows:

Wood ash: about 4.2 kg, (= 8% of total initial weight of wood burnt). Volume of ash about 12.500 cm^3; specific density of ash about 0.34.

Ash and residue of flesh: 0.6 kg (= 4% of total weight of flesh burnt).

Bone fragments (very small): small scales, friable and porous, outside white, inside black.

Soft matter: two or three pieces were carbonized and friable, easily breakable. Internally, they appeared to be carbonized, like soot. The third piece, oval in shape (about 13 by 7 cm, weight about 0.3 kg) was very dense and hard. Under the black crust it had an earthy appearance.

4.4. Conclusions

The heat produced by the combustion, not being able to spread to the outside, concentrated on the flesh above; this explains the good performance of this system: 3.5 kg of fuel per kilogram of flesh.

The experimental burning of beef in a furnace open to the front and at the top yielded a consumption of 3.1 kg of wood per kilogram of flesh, and produced 5.1% of ash from the flesh and 2.5% from the wood. Regarding the ash from the flesh, we must remember that it stemmed exclusively from bone matter, whereas in the case of the pit it came from soft parts of the carcass. The experiment in the furnace lasted 2 hours and 40 minutes. This rather long duration is due to the fact that the incineration of the residue on the grid necessitated such a long period of time. In the pit, combustion stopped after 1 hour and 35 minutes, but the result was an incomplete combustion.

A comparison of the two experiments shows that the fuel efficiencies are quite similar, but the performance, in terms of space, is clearly superior in the case of the furnace. The latter can, in fact, be operated continuously, whereas the pit has the disadvantage that the embers remain hot for too long a time and it is necessary to clean them out from the pit after they have cooled.

For the pit to function efficiently, the arrangement of the wood is very important. The logs must have a small cross section area if they are to burn easily and completely, and they must be laid out crosswise in the form of a grid. In the experiment described above, the initial load was 42 kg per 0.255 m³ of space, corresponding to 165 kg/cm³. We may specify 150 to 200 kg of wood per cubic meter of pit space for a satisfactory operation.

For easy and safe lighting it is important to place a layer of thin and easily flammable material over the bottom of the pit and to douse the inside of the pile with a combustible fluid. The process must, moreover, be carefully watched.

As was to be expected, combustion in a field furnace gave the best results in terms of fuel efficiency: 2.63 kg of wood per kilogram of incinerated flesh. This corresponds to about 152 kg for a corpse weighing about 58 kilograms.[14]. In view of the fact that the Gorini furnace (with direct firing) required 100 to 150 kg of wood bundles[15] for the cremation of a normal corpse, the field furnace in our experiment functioned like a wood-fired crematorium and the consumption of 152 kg of wood for a corpse of 58 kg must be considered the theoretical minimum limit. Actually, in a larger furnace, such as would be needed for the cremation of a corpse of 58 kg, heat losses due to conduction, radiation, and heat of the flue gases (higher excess of air) would necessarily be higher, and thus we would also have a higher consumption of fuel.

Photo 16

Photo 17

With respect to the incineration in a pit, the fuel-to-flesh ratio cannot be less than 3.5, because during the small-scale experiments thinly split and easily inflammable wood was used, and this procedure is practically impossible to use on a large scale. For a corpse of 58 kilograms one must therefore assume the consumption of at least 200 kg of wood.

The technical conditions for the study of mass burnings in swampy terrain are therefore the following:

• a single layer of corpses
• a load of 1.5 corpses per sqm (1 corpse per 0.66 sqm)
• a consumption of 200 kg of wood per corpse.

4.5. The Cremation of Corpses on Pyres

The above conclusions are perfectly compatible with practical experience. In India, in fact, cremation on a pyre is still an everyday practice. At Chandigarth, in sector 25, a total of 35 quintals of wood are used for the daily cremation of seven to eight corpses, an average of 437 to 500 kg per corpse.[16] According to the review Hindustan Today[17]

In other words, for the cremation of 21,000 corpses 8,100 tons of wood are needed, corresponding to 226.6 hectars of forest, for an average of 385 kg of wood per cremation.

A report on the wood requirements in urban areas in India states:[18]

The Hindu population being averse to abandoning the traditional practice of pyres, a so-called “fuel efficient crematorium” has recently been introduced in an effort to reduce the consumption of wood. In practice, this is an open furnace of the type I used for the experiment described in section 4.2.[19]. This device needs only half the amount of wood necessary for a cremation on a pyre (400 to 600 kg), i.e., 200 to 300 kilograms.[20] In January of 2002, several furnaces of this type were set up in ten villages of the district of Ludhiana. The newspaper running this news item stated that with the new technology

Photo 18

Photo 19

Photo 20

Hence, the consumption of 200 kg of wood for the cremation of a corpse in a pit, as assumed above, would appear to be a conservative estimate.

5. Combustion Experiments with Animal Fat (Lard)

The experiments described below were conducted by me with the aim of testing the significance of the witness statements describing the recovery of boiling human fat from the alleged cremation trenches at Birkenau.

The witness who has given the most detailed description of this alleged procedure is Filip Müller. He wrote that in the yard to the north of crematorium V, two trenches each 40 – 50 meters long, 8 meters wide and 2 meters deep (as well as another 3 for which he gave no dimensions) had been dug; two channels some 25 – 30 cm wide had been scraped out lengthwise from the center of the bottom and sloping down towards the ends, ending in what Müller calls “collecting pans,” near the ends of the trenches. According to this testimony, the two channels had the purpose of catching and transporting to the “collecting pans” the human fat that oozed out during the burnings. Members of the so-called 'Sonderkommando' then scooped the boiling fat out of the reservoirs by means of buckets attached to metal rods and poured it over the pyre to feed the combustion.[22]

Such a tale appears absurd for the following reasons:

1. The boiling temperature of animal fat is around 200°C, which is considerably higher than the flash point of animal fat, which is 184°C.[23] This means that boiling animal fat catches fire in the presence of flames of sparks.
2. Animal fat has an ignition point of ca. 280°C, which means that at temperatures of 280°C or more it ignites even without any external help from flames, sparks, or embers. Since the minimum temperature of a carcass combustion is 600-700°C, any fat would ignite instantaneously. If the temperature is lower than 600°C, “at the start of the cremation a distillation accompanied by a carbonization” occurs.[24]
3. The members of the so-called 'Sonderkommando' would have had to carry out their recovery of human fat on the edge of a cremation trench of at least 320 m², the surface of which was aflame at a temperature of at least 600°C! As we have seen above, during my small-scale experiment the temperature near the edge of the small pit reached some 120°C! An experiment aimed at studying prehistoric pyres was carried out by Dr. Alistair J. Marschall, who reports that he used a pyre made from one ton of wood to burn the carcass of a sheep. According to his statements, the fire became so intensive that after about one hour it was impossible to move closer than 3 meters to the pyre.[25]

Notwithstanding all this, I have carried out three experiments regarding the recovery of fat, which I shall describe below.

5.1. Experiment Involving Direct Heating

On the combustion grid of a furnace open in front and at the top, I placed an aluminum pan containing 500 grams of lard (see photograph 18). The combustion grid was situated at a level of 35 cm above the hearth grid. Once the firewood had been ignited, the fat melted rapidly and started to boil. The vapors caught fire, producing intensive flames that reached a height of some 80 cm (see photograph 19). Combustion lasted about 2 minutes.

5.2. Experiment with Heating by Radiation

The experiment was carried out in a furnace made of tuff blocks, open to the front and at the top.

On the bottom of the ash compartment I placed an aluminum pan containing 250 grams of lard. The hearth grid was at a level 25 cm above the ash compartment. It consisted of a metal wire-mesh net having openings 2 by 1 cm in size; thus, only small pieces of embers fell into the pan. The fat in the pan melted and started to boil under the influence of the heat radiating from the hearth; the vapors emanating from the fat caught fire rapidly and burnt with bright flames (see photograph 20).

5.3. Experiment with Heating by Conduction (and Radiation)

Photo 21

Photo 22

The experiment was carried out in a furnace made of tuff blocks, open to the front and at the top (see photograph 21).

I placed a pan containing 250 grams of lard on the bottom of the ash compartment as in the preceding experiment, but I installed a grid of a metal wire-mesh with larger mesh size (10 by 10 cm) at a level 28 cm above the ash compartment. Then I lit the wood on the hearth. When the combustion had become strong enough, the embers began to fall into the pan below; the fat contained therein first melted, then was absorbed by the ash particles and burned with a flame less bright but for a longer period of time (about 15 minutes), in the way the wick of a petroleum lamp would burn (see photograph 22).

5.4. Conclusions

1. The experiments show that animal fat, when heated to a temperature that can be reached by means of a wood fire, will burn readily.
2. Experiment 3 demonstrates that animal fat, when in contact with glowing embers, will ignite. Consequently, in a cremation trench, the human fat oozing out of the corpses and dripping through the burning wood, possibly reaching the layer of embers at the bottom of the trench, would burn without being able to flow over the bed of embers towards the alleged reservoirs. This was confirmed later by the experimental incineration in a furnace as described above, during which the fat dripping from the flesh into the ash tray ignited immediately and burned.
3. Experiment 2 demonstrates that any liquid fat, hypothetically dripping down below the embers into the alleged recovery channels, would burn under the effect of radiation from the glowing embers and by contact with them.
4. Experiment 1 demonstrates that human fat, hypothetically flowing into the recovery reservoir would, on account of the heat radiation from the fire, burn with bright and high flames, making it impossible not only to recover the fat, but also to get anywhere near the edge of the trench.

Notes