Now we turn to the question of HCN concentration.. Green's objections:
6) that 0.3-1% is an accurate claim of the concentrations used in gas chambers in the US.
7) that one should use 1% rather than 0.3%
Here is one of Rudolf's statements on concentration:
Leuchter speaks of concentrations of hydrogen cyanide used in executions in the USA in the order of magnitude of 3,200 ppm. In these cases, death occurs after 4 to 10 minutes, depending on the physical constitution of the victim.443
443 F. A. Leuchter, Boston, FAX to H. Herrmann dated April, 20, 1992, as well as private communication from Mr. Leuchter.
As we've seen, 4-10 minutes is probably overly optimistic.
This is what the first Leuchter Report says:
The first gas chamber for execution purposes was built in Arizona in 1920. It consisted of an airtight chamber with gasketed doors and windows, a gas generator, an explosion proof electrical system, an air intake and exhaust system, provision for adding ammonia to the intake air and mechanical means for activating the gas generator and air exhaust. The air intake consisted of several mechanically operated valves. Only the hardware has changed to the present.
The gas generator consisted of a crockery pot filled with a dilute solution (18%) of sulfuric acid with a mechanical release lever. The chamber had to be scrubbed with ammonia after the execution, as did the executee. Some 25 13-gram sodium cyanide59 pellets were used and generated a concentration of 3200 ppm in a 600 cubic foot chamber.60
Leuchter's history is incorrect. The first gas chamber was in Nevada. Arizona didn't build a gas chamber until the 1930s. Given this, I'm not sure what to make of his figures of 25 13-gram pellets and a 600 cubic foot chamber.
Germar Rudolf comments:
Equivalent to 17 m3, resulting in 10.5 g HCN/m3 = 0.87% by volume = 8,700 ppm. Experiments show that almost 50% of the HCN developed stays dissolved in the aqueous sulfuric acid (see chapter 126.96.36.199. of my expert report, G. Rudolf, The Rudolf Report, Theses & Dissertations Press, Chicago 2003, p. 265). Hence Leuchter’s concentration of 3,200 ppm is reasonable, although perhaps a little on the low side (depending on the volume of sulfuric acid used).
There are some problems with this account that need to be cleared up. First, Rudolf uses a conversion factor of 1 ppm = 1.2 mg/m^3 (see his footnote 339, or just observe what he did in converting 10.5 g/m^3 to 8,700 ppm). This is incorrect. The factor normally given is is 1 ppm = 1.1 mg/m^3. This will depend on temperature and pressure, but 1.2 is certainly too high. (Perhaps Rudolf was thinking of ppm by weight – depending on the temperature, 1.2 might be a reasonable figure for that.)
Therefore the figure 8,700 ppm needs to be corrected to around 9,500 ppm. If we take 50% of that, we get 4,750 ppm; if we use the exact results of Rudolf's experiment in chapter 188.8.131.52 and multiply by 20/37, we get 5135 ppm. It's clear already from this that Leuchter's estimate is significantly too low. (We will have to come back to Rudolf's experiment of chapter 184.108.40.206, because it was performed with KCN rather than NaCN, and because the conditions it used wrt temperature and humidity may not reflect those of US gas chambers.)
There is another reason to be suspicious of the figure 3,200 ppm: Leuchter uses it even when it contradicts the other figures he is giving. (Based on the first Leuchter report, it also seems that he was under the incorrect impression that 3,200 ppm is the lower explosion threshold for HCN.) Consider this document from the third Leuchter report (Fig. 72: Document series of a proposal for the construction of an execution gas chamber by Fred A. Leuchter Associates for the State of Missouri, dated December 31, 1987.)
In section 3.000, Leuchter, writes that a concentration of 3200 ppm "would be reasonable in a 600 CF chamber to ensure rapid death. This is a volume or approximately two (2) cubic feet of gas at a weight of 120-150 grams." The figure 2 cubic feet is fine - 2/600 = 1/300 = 3,333 ppm. The problem is that 120-150 grams of HCN are much more than two cubic feet or 3,200 ppm. Six hundred cubic feet is 17 cubic meters, so 120 grams comes to 7.06 grams per cubic meter, or some 6400 ppm, and 150 grams is some 8000 ppm. These figures are only a proposal, so we can't take them as actual, but they show that 3,200 is not an accurate figure – it is much too low (again).
This calculation ignored the fact that US gas chambers are underpressurized (a point I'll come back to later), but that factor would increase the concentration (by volume) that a given weight of HCN represents, so factoring it in would increase the error.
There is also some question over Leuchter's figure of 600 cubic feet. In section 3.000 as quoted above, Leuchter uses 600 cubic feet in estimating the quantity of HCN required; however, in section 2.002 of the same document he describes the gas chamber as follows:
It is a welded steel polygon containing twelve (12) sides of varying dimensions measuring a 7.5' diameter in one direction and an 8' diameter in the other. It is 8.5' high and has a volume of some 510 cubic feet.
The figure 510 cubic feet comes from multiplying 7.5*8*8.5. But that gives a large overestimate of the volume! It would be correct for a rectangular prism. To get the correct volume, two factors require correction:
(1) the base of the gas chamber is 12-sided (6 sides are very short, so it's approximately 6 sided), not rectangular
(2) the gas chamber slopes towards its apex; the top segment is not a prism but a pyramid.
Let's start with the first factor. Leuchter uses the figure 7.5*8 = 60 square feet for the area of the base. How do we correct this?
First off, there's the question of whether Leuchter's measurements are edge to edge or corner to corner. They must be edge to edge, for the following reasons:
(1) in examining the diagram of the Mississippi (not Missouri) gas chamber in the third Leuchter report (figure 70) with a screen ruler, there are pairs of parallel edge pairs matching Leuchter's description (short edge pairs and long edge pairs), whereas all measurements from corner to corner are equal or very nearly so, never in ratio near 8/7.5. Granted, this is a different gas chamber, but the shapes are roughly the same – 12 sides, every other one very short; they were both made by the same company (Eaton metal products).
(2) when measuring volume by multiplying dimensions, it doesn't make any sense to measure corner to corner; Leuchter would have known this (even though he was just making a rough estimate)
Also, assuming the measurement is edge to edge leads to a larger area than assuming it is corner to corner; thus to a lower HCN concentration. So if it did turn out that the measurements were corner to corner, the concentration would be adjusted upward, and our argument would just get a little stronger.
Method one: approximate the gas chamber by a regular hexagon whose sides are 7.5 feet apart. This will give an overestimate, because the shape of the gas chamber is derived from such a shape by chopping off all six of the corners, thereby reducing the area. The area of a regular hexagon whose sides are 7.5 feet apart is 48.713928975 square feet, or 0.811898816 times Leuchter's figure.
Method two (more accurate): assume that the shape (but not the size) of the Missouri gas chamber was the same as that of the Mississippi gas chamber (this is approximately accurate, as can be verified by finding images of both of them in the third Leuchter report and on flickr), and use figure 70 from the third Leuchter report. The pairs of sides matching Leuchter's description are, in my copy of the image, 422 and 396 pixels apart (422/396 is a fairly good match for 8/7.5, certainly within the uncertainties of the measurements). Leuchter's method of multiplying these dimensions gives a area of 167112 square pixels. We need to subtract the areas of the regions that fall outside of the of the dodecagonal base of the gas chamber but inside the rectangle drawn around it whose area Leuchter calculated. These regions can be divided into 4 small triangles, 4 large triangles, and 4 rectangles; I measured them with a screen ruler as follows:
20 * 36 pix
20 * 36 pix
22 * 32 pix
23 * 37 pix
20 * 85 pix
20 * 90 pix
22 * 87 pix
23 * 90 pix
85 * 156 pix
90 * 158 pix
87 * 152 pix
90 * 152 pix
Routine computation of the areas shows that we have the following:
area of little triangles: 1497.5 sq pix
area of large triangles: 27192 sq pix
area of rectangles: 7484 sq pix
total: 35173.5 sq pix
This is 21.6462612% of the total area, to our figure after subtraction will be 0.783537388 times Leuchter's figure.
Given the results of these two methods, I feel comfortable using the multiplier 0.8 to correct for the fact that the chamber is not a rectangle but a dodecagon formed by de-cornering a hexagon. Multiplying Leuchter's base are of 60 square feet by 0.8 gives an area of the base of 48 square feet.
Now onto the second problem:
To figure out how much to reduce the volume because of the pyramid on top, we need to calculate the height of the pyramid. We will use the height of the door to estimate the height of the chamber without the top pyramid. Leuchter states that the door is 80 inches high. Using a screen ruler and these two imageshttp://www.flickr.com/photos/[email protected] ... otostream/http://www.flickr.com/photos/pafringe/5 ... otostream/
I estimate that the door is 93% of the height of the portion below the top pyramid. That makes the portion below the top pyramid 86 inches high, or 7' 2''. That makes the pyramid 16 inches high.
However, I also calculated the height of the pyramid by assuming that the angle of ascent along the faces of the pyramid is the same in MO as Leuchter says it is in MS (31 degrees) and found that the pyramid is 2.25 feet high. Going by the images, the angle of ascent in MO is less than in MS, but to make the height just 16 inches it would have to be a little under 20 degrees, and I don't think it's that small. Part of the problem may be that Leuchter's measurement is off by a few inches (which wouldn't be surprising, since he was rounding to the nearest half foot). The other issue is that the top segment is not really a pyramid, but a truncated pyramid. I'm going to estimate that the full pyramid would be 20 inches high, and the truncated pyramid was correctly estimated at 16 inches.
Calculating the volume of that truncated pyramid gives 26.45 cubic feet, plus the rest of the gas chamber (area of base 48 square feet, height 7'2'') which has volume 344 cubic feet, for a total of 370.45 cubic feet.
Given our new volume, we can see that if 120-150 grams of HCN were released in the MO gas chamber the resultant concentrations would be 11,400 – 14,300 mg per cubic meter (divide by 1.1 to get ppm – provided you ignore the underpressure issue). Not 3,200 ppm but over 10,000!
If course, the figure 120-150 was just a proposal, not something that was actually used. If the amount of cyanide used was the 25 thirteen gram sodium cyanide pellets that Leuchter mentioned in connection with the first execution, assuming with Rudolf that half of the HCN produced actually gasifies, then the concentration of HCN would be 8,500 ppm (ignoring underpressure). Again, 3,200 is way too low.
In the third Leuchter report, Leuchter gives another figure:
The chemicals used by Mississippi are an approximate 37% Sulfuric Acid Solution (acid and distilled water) and an approximate 16 ounces of sodium cyanide. This requires twelve (12) pints of distilled water and six (6) pints of acid (98%), resulting in 18 pints of dilute sulfuric acid reacting with 24 briquets of sodium cyanide. This results in two (2) cubic feet of Hydrogen Cyanide gas at the 10 psi (approximate) operational pressure or an amount of approximately 7500 ppm.
This is more reasonable than the 3,200 figure, but note the full 16 ounces of NaCN. This will yield 250 grams HCN; if half remains dissolved that's 125 grams of HCN in the chamber. What is the chamber's volume? Leuchter describes it like this
It is hexagonal in shape, but with the corners replaced with the base of an equilateral triangle whose theoretical third angle would have been the original corners of the hexagon. The base of this triangle measures some 7”. Thus, each corner is actually two seams instead of one, each seam being one of the base angles of the equilateral triangle. The roof of the chamber is fabricated by a continuation of the side segments at pitch of some 31 degrees from the horizontal. The height of the roof is some 23” above the top of the chamber. The chamber measures some 6’ 2” in diameter from corner to corner and some 8’10” high in the center. The floor area of the chamber is about 29.7 square feet and the volume of the chamber is some 263 cubic feet.
The figure he gives for the area of the base – 29.7 square feet – fits pretty well with the other measurements he gives, so I'm happy to use it. The volume of 263 cubic feet, however, results from multiplying the area of the base by 8'10'' – we have our second problem again, that of the pyramid on top. I won't bore everyone by writing out all the details again – I used a screen ruler on this image
and Leuchter's statement that the door is 77 inches high; there are some complications as the different data don't all quite agree. Using the height of the door and the screen ruler yields a lower height for the prismatic portion of the chamber than using Leuchter's angle of ascent and subtracting off his total height. My best guess, though, is that the volume is around 225 cubic feet.
Now, 125 grams in 225 cubic feet is 19600 mg / m^3 = 17800 ppm (ignoring the underpressure). Using Leuchter's figure of 263 cubic feet would give 15250 ppm. Unless for some reason a much greater percentage of the HCN produced remains dissolved in US gas chambers than did in Rudolf's experiments, the figure of 7500 ppm is much too low.